@ck0 Thanks for your suggestions. After going down a rabbit hole, I think the closest thing to what I'm interested in would be this project:
"OAuth 2.0 & OIDC Auth Server and Identity Provider"
https://github.com/vigiloauth/vigiloIt's
#OpenSource, and it's written in
#Golang. Having said this, it's only alpha quality at this time, and has been sitting stale for a year. Some sort of funding/money would be great to keep this project moving forward. IMHO, it should be organizations such as the
#LinuxFoundation or maybe even
#NLnet who should be taking an interest in this.
Honorable mention to lemonldap-ng (has stock Debian packages, and they have a Mastodon account), but I sort of disqualified it from consideration owing to LDAP (I'd like to just 100% leave it behind, same with SAML), and also that it's written in Perl.