The only serious attempt I’ve seen is https://creatr.nostr.wine . I am not in favor of using paywalls this way, however, so I cannot speak to how effective it has been as I have not tried it. I think @𝕾𝖊𝖗 𝕾𝖑𝖊𝖊𝖕𝖞 tried it at one time. Maybe he has some insight.