It's crazy SimpleX is fine being based there. I mean, everything is open, the clients have reproducible builds, but it seems like it may end up being a hassle.

Has the UK started attacking any open source E2EE projects yet?

Apple's control over iOS is the main reason I prefer GrapheneOS so much over it. You get amazing privacy and security without sacrificing control. GrapheneOS has said they won't introduce age verification and a backdoor they obviously won't implement.