Played around with it a bit more. I’ve created a patch/polyfill file that correct does Object.fromEntries and now WebGL2 works. It also adds a stub for the import function.
This means that for now, you don’t have to build a custom version of the engine. You can use the one that the build ships with.
I also added a polyfill for promises so that the current version of Ammo used by the Editor can load too.
With this, you should be fine 
for PlayCanvas to run on those TVs with minimal hacks.
My Food Run project fork has been updated: https://playcanvas.com/project/1187223/overview/food-run-pre-62
Patch file to be loaded before the engine:
/*
Copyright 2018 Alfredo Mungo <alfredo.mungo@protonmail.ch>
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to
deal in the Software without restriction, including without limitation the
rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
IN THE SOFTWARE.
*/
if (!Object.fromEntries) {
Object.defineProperty(Object, 'fromEntries', {
value(entries) {
if (!entries || !entries[Symbol.iterator]) { throw new Error('Object.fromEntries() requires a single iterable argument'); }
const o = {};
Object.keys(entries).forEach((key) => {
const [k, v] = entries[key];
o[k] = v;
});
return o;
},
});
}
if (!window.import) {
window.import = function() {}
console.log('Stubbing out import function');
}
// Copyright (c) 2014 Taylor Hakes
// Copyright (c) 2014 Forbes Lindesay
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
!function(e,t){"object"==typeof exports&&"undefined"!=typeof module?t():"function"==typeof define&&define.amd?define(t):t()}(0,function(){"use strict";function e(e){var t=this.constructor;return this.then(function(n){return t.resolve(e()).then(function(){return n})},function(n){return t.resolve(e()).then(function(){return t.reject(n)})})}function t(e){return new this(function(t,n){function r(e,n){if(n&&("object"==typeof n||"function"==typeof n)){var f=n.then;if("function"==typeof f)return void f.call(n,function(t){r(e,t)},function(n){o[e]={status:"rejected",reason:n},0==--i&&t(o)})}o[e]={status:"fulfilled",value:n},0==--i&&t(o)}if(!e||"undefined"==typeof e.length)return n(new TypeError(typeof e+" "+e+" is not iterable(cannot read property Symbol(Symbol.iterator))"));var o=Array.prototype.slice.call(e);if(0===o.length)return t([]);for(var i=o.length,f=0;o.length>f;f++)r(f,o[f])})}function n(e,t){this.name="AggregateError",this.errors=e,this.message=t||""}function r(e){var t=this;return new t(function(r,o){if(!e||"undefined"==typeof e.length)return o(new TypeError("Promise.any accepts an array"));var i=Array.prototype.slice.call(e);if(0===i.length)return o();for(var f=[],u=0;i.length>u;u++)try{t.resolve(i[u]).then(r)["catch"](function(e){f.push(e),f.length===i.length&&o(new n(f,"All promises were rejected"))})}catch(c){o(c)}})}function o(e){return!(!e||"undefined"==typeof e.length)}function i(){}function f(e){if(!(this instanceof f))throw new TypeError("Promises must be constructed via new");if("function"!=typeof e)throw new TypeError("not a function");this._state=0,this._handled=!1,this._value=undefined,this._deferreds=[],s(e,this)}function u(e,t){for(;3===e._state;)e=e._value;0!==e._state?(e._handled=!0,f._immediateFn(function(){var n=1===e._state?t.onFulfilled:t.onRejected;if(null!==n){var r;try{r=n(e._value)}catch(o){return void a(t.promise,o)}c(t.promise,r)}else(1===e._state?c:a)(t.promise,e._value)})):e._deferreds.push(t)}function c(e,t){try{if(t===e)throw new TypeError("A promise cannot be resolved with itself.");if(t&&("object"==typeof t||"function"==typeof t)){var n=t.then;if(t instanceof f)return e._state=3,e._value=t,void l(e);if("function"==typeof n)return void s(function(e,t){return function(){e.apply(t,arguments)}}(n,t),e)}e._state=1,e._value=t,l(e)}catch(r){a(e,r)}}function a(e,t){e._state=2,e._value=t,l(e)}function l(e){2===e._state&&0===e._deferreds.length&&f._immediateFn(function(){e._handled||f._unhandledRejectionFn(e._value)});for(var t=0,n=e._deferreds.length;n>t;t++)u(e,e._deferreds[t]);e._deferreds=null}function s(e,t){var n=!1;try{e(function(e){n||(n=!0,c(t,e))},function(e){n||(n=!0,a(t,e))})}catch(r){if(n)return;n=!0,a(t,r)}}n.prototype=Error.prototype;var d=setTimeout;f.prototype["catch"]=function(e){return this.then(null,e)},f.prototype.then=function(e,t){var n=new this.constructor(i);return u(this,new function(e,t,n){this.onFulfilled="function"==typeof e?e:null,this.onRejected="function"==typeof t?t:null,this.promise=n}(e,t,n)),n},f.prototype["finally"]=e,f.all=function(e){return new f(function(t,n){function r(e,o){try{if(o&&("object"==typeof o||"function"==typeof o)){var u=o.then;if("function"==typeof u)return void u.call(o,function(t){r(e,t)},n)}i[e]=o,0==--f&&t(i)}catch(c){n(c)}}if(!o(e))return n(new TypeError("Promise.all accepts an array"));var i=Array.prototype.slice.call(e);if(0===i.length)return t([]);for(var f=i.length,u=0;i.length>u;u++)r(u,i[u])})},f.any=r,f.allSettled=t,f.resolve=function(e){return e&&"object"==typeof e&&e.constructor===f?e:new f(function(t){t(e)})},f.reject=function(e){return new f(function(t,n){n(e)})},f.race=function(e){return new f(function(t,n){if(!o(e))return n(new TypeError("Promise.race accepts an array"));for(var r=0,i=e.length;i>r;r++)f.resolve(e[r]).then(t,n)})},f._immediateFn="function"==typeof setImmediate&&function(e){setImmediate(e)}||function(e){d(e,0)},f._unhandledRejectionFn=function(e){void 0!==console&&console&&console.warn("Possible Unhandled Promise Rejection:",e)};var p=function(){if("undefined"!=typeof self)return self;if("undefined"!=typeof window)return window;if("undefined"!=typeof global)return global;throw Error("unable to locate global object")}();"function"!=typeof p.Promise?p.Promise=f:(p.Promise.prototype["finally"]||(p.Promise.prototype["finally"]=e),p.Promise.allSettled||(p.Promise.allSettled=t),p.Promise.any||(p.Promise.any=r))});
