First of all, very cool thing that you've built 👏

paywalls are common and there has been many open source versions built with Lightning over the years but I like the idea of "one time use" links which technically sounds a lot like L402 stuff which you can time lock or restrict in other ways as well.

Please don't use cashu but look into glowpay by breeze which is basically self custodial instant LN receive and that'll make it a good enough UX for sellers.

Now will you actually get buyers? That's the big if and all the best of luck.