One of my current beefs with Facebook is that they have gated their API access behind requiring a "verified business account", which IMO doesn't really have the hobbyist developer in mind. (This decision arguably makes sense for them, but it's inconvenient for me.) Specifically, I want to implement Facebook login for my reciprocity clone, so people can see (and be visible to) and tick only their friends, but currently I can't.

It looks like friendica is likely to be more pliant. You can fetch your list of followers with HTTP basic authentication:

CREDS="username:password"
ID=$(curl --silent -u "$CREDS" https://superstimul.us/api/account/verify_credentials | jq .id)
curl -u "$CREDS" https://superstimul.us/api/v1/accounts/"$ID"/following

You can also see the following list of other users (presumably subject to their privacy controls) by replacing your ID with theirs. (This requires authentication.)

OK, so getting who follows who is easy enough. reciprocity also needs to know which user you are (in a way that can't be impersonated but doesn't involve handing over your login credentials). From the docs, it sounds like it supports OAuth 1 in addition to HTTP basic auth, which I hope would be able to do that. (Seems like it doesn't support OAuth 2 or OIDC.)