Two major instanced collections limitations

I’ve just found out about two annoying limits while using collections.

  1. It’s not possible to override the Object ID pass for instanced collections.
  2. Instanced collections cannot be used as fluid obstacles.

Are these known limitations?

One workaround for the Object ID could be using Cryptomatte, though last time I checked I couldn’t properly read the Cryptomatte pass in Fusion.
As for the fluid obstacle, the only solution I can think of is to create dummy objects that resemble the collection’s mesh. Still, quite a slowdown, and not efficient.

Any thoughts?