What exactly do you need this for? If it's for authenticating with their IMAP/SMTP, app passwords have worked for me with Gmail, even on 2FA-secured G Suite accounts. No idea about Microsoft though.
Exchange administrators usually disable IMAP. K-9 originally was one of the few apps that could still talk to Exchange servers. But it's failed to keep up with the times.
Currently you have to allow "less secure apps" on your Google account to use K-9.
https://support.microsoft.com/en-us/account-billing/using-ap...