Hosting oAuth1 or oAuth2 Server

I understand there is support for external oAuthX providers, but if I would like to implement oAuth1 or oAuth2 with ServiceStack, is that supported? I would like to be able to build an API with ServiceStack where third party apps can use the logins of our API but with a grant from the user (as you see when you use Google, Facebook account for your app).
Is this possible?
I know there is a JWT provider but this only support sending uid/pwd through the client.

In .NET Core you’d typically use IdentityServer to create an OAuth Server, e.g:

I’d personally recommend keeping the OAuth Server independent from your Apps, i.e. treat it like a 3rd Party OAuth Provider and not try bundle it with your existing Apps.

Just to be sure I understand properly this template could be use for like an “Azure B2C” service and base on that provide an SSO solution for our different apps?

It’s for using as your Auth Server and includes integration examples of separate ServiceStack Web Apps and APIs that uses it for authentication.

See using IdentityServer4 Auth docs for more info about this template.