> How will this work with chat control?
There is no POC for a chat control E2E-compliant chat app and there will never be. this will just kill EU made software because they will be forced to comply, while US software will use real E2E as marketing.
Chat control (which isn't (yet) a thing) would not in fact lead to the outcome you describe.
Any company would be forced to comply or get the boot from EU market. Apple and Google will happily enforce that and that's probably good enough initially.
US Vendors could also decide to create an EU only version of their services.