Donations; things like Patreon or whatever. If you enjoy someone's content and are financially stable you have a bit of a moral obligation to give them a bit of money for it. Likewise, you should give your instance admins a few bucks to cover their hosting costs.

Creators could use the Fediverse to show off their products in order to get people to support them on Patreon (or Subscribestar or Ko-Fi or your subscription platform of choice). Or maybe even get them to buy their products on Itch, Bandcamp, Etsy, Steam and so on. Twitter and Reddit never really were ways to make money, but instead a way of pulling people towards other revenue streams.

The traditional model where people get paid by ads (such as Youtube or Twitch) is honestly dying with the rise of adblockers. Although I could imagine people on the Fediverse running a "premium subscription" plan and sharing their revenue with creators like Youtube Premium though.

For a full fediverse alternative to Stripe/Patreon/Paypal that isn't crypto based? Probably not going to happen. Besides the technical challenges, you need a good rapport with payment processors that you can only get if you are a big company and comply with their demands (which many fediverse instances would not be willing to sacrifice their morals to do).