So today I added this to the weblog. It can now do the extra verification that happens, because of PKCE. It was pretty simple as you can add it as a few steps between the normal authentication. The structure itself stays very much the same.
So this was the authorization server side of the protocol. Now I should add this to the clients that I created. link
This website was created by Peter Stuifzand.
Currently I'm testing micropub, microsub and working on Indieweb things.