A couple of friends and I have been working on Shopstr for a bit now and recently launched. It's definitely still a work in progress but for now you can check it out at here. We currently support NIP-04, NIP-07, NIP-09, and NIP-99 and also have a PWA. In the near-future we're planning on adding a native Cashu wallet and NIP-15 support. Any feedback is greatly appreciated.