The Hoot team has been working on one: https://github.com/ProjectHoot/hoot-mobile/
Using webfinger requires HTTPS because it's defined that way in the webfinger spec.
Federation with non-secure instances is currently allowed otherwise but shouldn't be (https://todo.sr.ht/~vpzom/lotide/132)
UPDATE person SET is_site_admin=TRUE WHERE id=1
(assuming 1 is your user ID)