Funny how I use TB on desktop as long as it exists and always wanted a android version and I even knew that is was in development and still this is the first time I heard that it was released. A little cross promotion wouldn't hurt.
I've used K9 for over a decade, until at some point work required me to have an exchange account. At that time I switched to Nine, since outlook is hot garbage.
Are there alternatives to Nine? I've used that for several years for my personal email because of exchange, but it has had issues the last couple of years. Not open source as far as I know.
Android 15 (LOS) on my LG G7 thinq 4gb ram, when I have a large number of accounts when syncing them android will run into oom issues even after tweaking oomd
There's Betterbird, though I don't know exactly what makes it better, except for still allowing to manually load external content in encrypted mails, which Thunderbird just removed for whatever stupid reason.