[NoGravitas]

Yes? But indieauth does not require you to personally run an auth server, which makes it easier to adopt. Basically it will search through different online identities that you list on your home page and letting you choose any of their OAuth services.

[Nullabillity]

Neither did OpenID, you would just list your auth server in a special meta tag. IndieAuth even seems to support acting as your OpenID server, see https://indieauth.com/openid .