I switched to FairEmail, which has too many options but supports OAuth.
If you have your own SMTP/IMAP with oauth support you cannot use either tool to log into it. The only actual software that I know which supports custom oauth configuration is Roundcube webmail. It also happens to work beautifully with postfix + xoauth.
By the way, the last time I was searching for an email client with oauth support I got the distinct impression that oauth was on its way out anyway.
People who created Inbox they should be proud of themselves!
It works with every service, handles the broadest range of attachments, is perfectly reliable, has no ads and has the best UI of any of them. I don't know why it exists, but I'm glad it does.
Still, it not being open source hurts. I wish Thunderbird worked on Android.
Im currently testing Canary, which doesnt seem to do that and so far its ok. But I K9 and Fairemail are definitely one of few apps Im missing since migrating to iOS.