I started adding #C2S #proxy_url support for #GoActivityPub services and it looks like it's easier than I imagined it initially.

On the server side, implementing the proxyURL handler doesn't need any new additions as it shares 90% code with other handlers that return #ActivityPub objects.

On the client side, I'm creating a new http.RoundTripper that can use the proxyURL transparently for the caller.

As a developer in your client code you only do a regular request for a remote URL, and the round-tripper handles the proxying part transparently if it has all the available bits: a server that supports proxyURL and a valid OAuth2 session towards that server.