No it is open-source and portable to any platform you want. We currently support iOS and Android through Play store and F-droid, but that is just because most of the market is there at the moment.

What about the "App and device verification based on Google Play Integrity API and Apple App Attestation" that was in the readme?

Was this discarded? Is it not necessary anymore? Can someone without writing their own implementation use the app without using any of those two?

I think we are talking about different things here. I think you are referencing the eu-digital-identity-wallet, which is a reference implementation. Our identity wallet precedes this wallet and never had this requirement.

What about devices without a hardware-based trusted computing module? Am I now limited to what hardware I can run before I even get to my custom software?