Another option is LNURL Zap where you can create an LNURL for any Nostr event and then put the QR code on your site. An anonymous zap is sent whenever someone pays the LNURL.
Discussion
Check out this plugin too
Took me a minute but I think nostr:npub12w53uwny68m936vr4s0yl8svd9lc7vlqrkx7hepe7nq6jggn7kfq92rrm3 is the author 🤙