Turns out Keyguard, an alternative Bitwarden client is already on the Play Store.
https://github.com/AChep/keyguard-app
Edit: turns out Keyguard is source available but fully copyrighted.
I skimmed the thread, so maybe I missed it, but from what I saw, saying they deliberately broke Vaultwarden is a bit if a stretch. They likely develop their apps without taking into account others (and rightfully so), and it happened to break an unsanctioned 3rd party implementation. Nothing nefarious.
The “nefarious” dividing line is often hard to assess. For a better-known example, it’s interesting just how many times Google has done things like degrading their stuff on Firefox by user-agent string detection, and then been all apologetic about it, it was a mistake, &c. Malice and incompetence can be indistinguishable.
I stand by that, but then again, this is about secrets management we’re talking about, so the organization would need a pretty high level of seriousness to be able to be trusted.
That’s a high bar for sure, but it looks to me like Bitwarden is trying to approach it from the top.