I want to instantiate an object in some specific coordinates in ARFundation, I have tried several ways but none convinces me or gives me the result that I want,
Does anyone have a proven way since it works and has enough accuracy?
Apple has released something called ARGeoAnchor.
I think it is not yet supported on Unity though.
If you wish, you can use it, with RealityKit been your engine. https://developer.apple.com/documentation/arkit/argeoanchor
Also, note it is only supported in distinct locations in the US.
From what I could tell so far, it is very accurate, with the problem only been the altitude you wish to put things on.