It's just people having zero product sense, or an idea of what it means to target more than 0.01% of the market. The last comment said that Signal's problem is that it's mobile-first, which, how does someone even think that a messaging app should be anything other than mobile-first?

Having Google and Apple apps is fine. Having that be the only option, and the recommended option for high risk use cases is unforgivable.

Those aren't the only two options. You can buy a non-Google Android phone and install the APK on it.

There are no fully open/auditable android phones. All of them have privileged binary blobs. An end to end chat service where there are no options permitting full accountability of the client software and operating system is largely security theater.

Even if you do all that, it is not an official option, let alone a recommended one. The recommendation is to accept the google or apple terms of service.

Moxie even went as far as to say he would actively do anything in his power to discourage or stop the use of third party clients.

Potentially targeted users are set up to fail.

How do I run Signal on my Librem 5?

Use something like gurk[0]

[0] https://github.com/boxdot/gurk-rs

You write an OS/2 emulator for it and use the OS/2 version of Signal, of course. How else?