What about a Thunderbird mobile app? (twitter.com)

To be honest, I'd rather they donated or collaborated with FairEmail[0], it's the best email client on Android by far, and although I use Thunderbird on PC I'm not sure what their android client could do that would make me move away from FairEmail.

0: https://email.faircode.eu/

Fairmail is simply the best

They should contribute to an existing mail app like FairEmail instead of creating another app.

I wonder if this is related to K9 mentioning they're in talks with Thunderbird

https://k9mail.app/2022/01/18/2021-in-Review