I'm really surprised sellers aren't trying to use it at all. There was a small push awhile ago ~2015/16 where a bunch of online stores started accepting bitcoin but IIRC they all stopped once the BTC/USD started to decrease.

I guess credit card fees are <4% so there might not be a big enough discount to offer consumers to make them figure out how to get crypto (without paying more than 4% fees somewhere). Perhaps a chargeback heavy industry such as porn or political groups could benefit from non-chargebackable transactions.