since i've read this community was created by mods of r/ProtonMail and chose to uncritically believe it, this is the closest we are to an officially lemmy presence, so...just to make sure this question is in every ProtonMail forum:
That would be lovely. There are few email clients available on fdroid and I've had issues with either anti features or getting the other ones to work with pop or IMAP.
I tried the actual email clients available on F-Droid because I host my own email server; so I am able to open up ports for mail to go in/out from my server. Half of the clients didn't even sync correctly with that (I've been configuring email for ages). I long for proton mail to offer me my backup email address on my phone.