nostr:npub1pww7030g95nv9ptfpgfu69jpfxj6pm33xxueztsupwekce45wx4sm6en60 made these two awesome tutorials on how to use coinjoin in BTCPay. 
https://www.youtube.com/watch?v=zGVCrwMKKn0
https://www.youtube.com/watch?v=g5nFckPfPcA

But the more the better!