This is super cool, Thanks for writing all this!
We have been exploring way and one of the most recent one is a custodial wallet, LifPay... it allows creating templates really easily. It works in two simple steps as follow:
  1. Creating
  2. Sharing with Buyers
It's fully anonymous and also provides a random LNaddress, ours is 908f0a0c@lifpay.me. We have no affiliation with the service, we just like it!
The link to download the file is available to buyer only after payment is successful. You can try it yourself from here https://lapp.lifpay.me/checkout/c678c75e-e1f4-4753-87d5-d818bb7ae617