K-9 is being used as the base for Thunderbird for Android but it isn't there yet. FairEmail is a lot closer in functionality at the moment.
I use Thunderbird for Gmail (among other accounts) and it has to regularly compress my Gmail box, which none of the Android clients do - in my experience, Aqua Mail, K-9 and FairEmail all struggle with a decent sized Gmail mailbox after a while.
"He called you three as well?"