I am not an expert, but chat control and interoperable protocols are two different things, aren't they? With stopping chat control you wouldn't stop the law that's restricting signal's e2e-problem.
Edit: As far as I can tell after searching a bit, interoperable protocols will be requiered by the DMA, but only for plattforms. So you seem to be right, that chat control will be the big jeopardy for smaller ones like signal.
Check out https://gitlab.com/Nulide/findmydevice But it will delete evrrything, I think.