I've made a list of some animal shelters which already accept Bitcoin donations, and could possibly be convinced to have a presence here on nostr (I'm sure there will be more than this, if you know any please add)
Edinburgh Dog and Cat Home
Location: Edinburgh, UK
Website: https://edch.org.uk/cryptocurrency-donations/
Farplace Animal Rescue
Location: UK
Website: https://www.farplace.org.uk/how-to-help/donate-cryptocurrency/
Best Friends
Location: Utah, US
Website: https://bestfriends.org/cryptocurrency-donations
Cochahuasi Animal Sanctuary (already accept lightning)
Location: Cochahuasi, Peru
Website: https://cochahuasi.com/bitcoin-donations/
Four Paws
https://www.fourpawsusa.org/get-involved/donate-to-the-animal-crypto-fund
Location: Wordlwide, US location: Boston
The Humane Society of the Pikes Peak Region accepts crypto currency. Not Bitcoin only. Its a start.