Shopify clone mini app (with Coinbase Commerce) and Gumroad clone mini app (can do direct payments here) would both be extremely valuable and you would be justified in taking txn fee or saas fee for them

We built this (except without all the middlemen). 

You can host your own storefront and start getting selling immediately, no sign-up needed. 

It also has an escrow feature so a 3rd party can mediate disputes, increasing buyer confidence

The Farcaster formerly known as Kchamp. Books, beats, bodybuilding, bright ideas and beautiful things.

katherinechampagne.com

We built this (except without all the middlemen). 

You can host your own storefront and start getting selling immediately, no sign-up needed. 

It also has an escrow feature so a 3rd party can mediate disputes, increasing buyer confidence
https://mini.ump-eth.xyz/

Check out my storefronts for an idea of how it works (the stickers are only ~$2 and if you have a base wallet with ETH in it, it's the smoothest purchasing experience ever).

We're building a lot of new features like custom storefronts and auctions, which should be done pretty soon.