Yes, that would be useful. Basically, what you have in https://github.com/infogulch/caddy-xtemplate/blob/master/tem... - but without Caddy dependencies and with a way to use any router library (I use gorilla/mux).

I would make the templates library take a callback function for every public template: func(method, path string, template).

Then the user could add any custom logic to register the route handler and execute the template with any application specific inputs.