With Prusaslicer 2.6.1 the feature of interlocking layers of paint on multi color areas was added and its a nice start.
but building on top of this it would be nice if it would be possible to interlock multiple objects.

right now as far as i know you can only have one object and paint on it and the painted on part can interlock with the rest, my proposal would be to give us an option to either tell the slicer to interlock object on the internal layers automatically so from the outside you couldnt even tell the difference between interlocked parts and those that have not been interlocked internally and/or extend the functionality of the paint tool so you can paint on where two objects are supposed to interlock.

ideally both options should be done at some point, automatic interlocking and paint on interlocking for cases where the automatic one doesnt provide the desired result.