google smtp relay and passkeys?

I have been using google as an SMTP relay with postfix for years with an
app password but it seems that is now made obsolete? Is anyone using this
successfully? I suspect the problem is that I use their passkey on my other
devices and that switches off name/password authentication everywhere. Not
ideal. If this is not resolvable — if I choose not to downgrade security on
my other devices to recover this — are there public relay servers anywhere?
I expect the answer is no but perhaps there is an authentication
method that helps keep them from being abused.

-- 
Paul Beard / www.paulbeard.org/