I just can’t find a decent email client that looks like it’s from the last 20 years. Geary and Evolution both appear to be pretty modern but something about using Gmail with a Yubikey just doesn’t work and neither of them will connect to my account. Both on Fedora and OpenSUSE. Thunderbird works but it’s so old fashioned and Betterbird doesn’t look much better. What’s everyone else using?
Wasn’t it supposed to become Thunderbird for android?
You are thinking of K9
You are mistaking KMail (desktop client by KDE) and K-9 Mail (Android client that is being rebranded into Thunderbird for Android).
I think this was a different smartphone app that would get the Thunderbird branding… searching… ah, it’s K-9: https://blog.thunderbird.net/2022/06/revealed-thunderbird-on-android-plans-k9/