Just spinned up my own instance of Keyoxide here: https://keyoxide.bismuth.it/
So you can do your identities GPG-based proofs on an instance other than the "main one" at keyoxide.org and base it on more "local" trust (if you trust my instance, that is :p)

For the moment it does not support Matrix and XMPP proofs, but i'll add the required config in the future :)