You have to selfhost bibliogram, working for me, I usually get rate limited but get all updates once or twice a week.

There is a facebook bridge in rss bridge, for a long time it worked, I don’t follow its development nowadays, maybe someone with some php knowledge can resurrect it.

With bibliogram you can follow instagram pages in rss: https://sr.ht/~cadence/bibliogram/

Facebook pages used to work with rss bridge: https://github.com/RSS-Bridge/rss-bridge