could a navigation(nav mesh) like in unity be added and AI system
It’s something that could be done (@Leonidas has made one that you can purchase Released: Hephauestus Grid Pathfinding). Unfortunately, it’s not that high on our priority list at the moment.
We have some really nice features in the pipeline, templates (prefabs), a new animation system, Basis texture and Draco mesh compression (to make downloads of games much smaller), official Editor API to allow for customisation, etc.
Although I am quite satisfied with how my AI functions with sensors (raycasts), I would also like to see a pathfinding system in PlayCanvas. In some environments, my AI now continues to roam between a number of obstacles. But maybe I can come up with a solution for that later.