@cassidyclown @mint @Tadano @ne @neet @ryo Yup, seems to work, my follow request went through. As for other instances, fedilist crawls onions, but most of them aren't too active. A bunch of mirrors ended up there as well, I removed them from the list.
$ curl 'http://demo.fedilist.com/instance/csv' --silent | grep \.onion\,
svfkzobwlzuxn46t4yfl5xolgh5gbi5hax5kfmfnzkz7a3fexw4jhfyd.onion,up,mastodon,0,0,8,1646252489
a232ncr7jexk2chvubaq2v6qdizbocllqap7mnn7w7vrdutyvu32jeyd.onion,up,mastodon,0,92,48,1644914514
64yuxt2vzvbfbcckwbyhagwgxtvvdc67ukfpvh6kjudow6jvgnhnlwyd.onion,up,mastodon,0,17,29,1645999447
liibeu7vlwaumwrstixzcpkqucdfln5m4sn5buciwkgbn6aet2xokzyd.onion,up,mastodon,2,21,64,1644914514
lm6qdqe5qbir26aqfsyogoo2mykxo4ff66ekfzpayflt6y5i7viiooid.onion,up,mastodon,0,73,59,1644914514
dq5dgaiq6cshrgyupj5yi3vzvipikpkopc6ht5kiiuikjngt74ybgqad.onion,up,mastodon,0,0,18,1644914515
fmxsd7f7qubflkkjb6ck4douwlckq5jf4b5x5fskpxik34hjfdtebead.onion,up,mastodon,0,7,40,1644914514
fbbtyosausdfn3ogl66spqj5prnu3tscokaijcimd3hwszoe5hc4r4yd.onion,up,mastodon,0,28,31,1644914515
zgz3oin6wbe7k37jokcaghd2bi3uezhuqdtac22hjlmhc4cgyw6s5yyd.onion,up,mastodon,1,29,59,1644914514
hqiww2qqev45zq3xadmwvegmq47hhi3a24ahnyed3ogadzdb5jl7m2qd.onion,up,mastodon,0,94,71,1644914514
p3dm56xwesyzqo7twt5v33t6qdm7aiapylfp7y5ioknkvarnfsovt2ad.onion,up,mastodon,1,127,40,1644914514
5z5ce433e2yp73jqm3yxmyh2yvcn33venhnm5trqde6uwjysxyy3gbad.onion,up,misskey,,,982,1644791248
rawrxd4mden7rmbobaftao3qjyxbrvj4rrooehkqxlqcsdtnnn2hndid.onion,up,pleroma,5,83,396,1658227745
chistqvhpsuxxxgccn3a7lqze24idsatjmkcqqqawwosflduy4utfyqd.onion,up,writefreely,25,225,,1644821564As for I2P, I know about pubsub.i2p (which only federates inside Tor and I2P, so no access to clearnet from their side) and iwojima's instance (which does federate with Tor and clearnet).