I somehow felt inclined to also try my hand at creating a #fedifinder -like tool, but with the premise, that it *really* does not require giving any data or access to your account to someone else's server.
Because of technical reasons, it can only be used with a CORS-proxy or by temporarily disabling CORS-checks, though.
Don't expect too much. It doesn't match up to Luca's app in the slightest and is more like a proof-of-concept and fun-project.
You can try it here: https://mapeper.github.io/twitter-mastodon-finder