This is the exact idea I had in mind. Offering a simple POS, a simplified bolt card manager (and offering the cards as well) charging very low for managing the service.

I tried the POS app, the web interface, everything works really great!!.

It would be nice if you could have a spanish translation as well.

What is the threshold on funds for them to deposit back to the onchain address?

Is the app manager site available for setting up other ntag424 cards? or is it only available for the cards you issue? Also on that, are the cards reusable whether on another account on your site or whether on other platform?

BTW I tried the app also on 32 bits android printer devices (like the sunmi V2 or Wiseasy). It works too! This might be usefull since many merchants are getting those devices for printing electronic receipts (now mandatory in many countries). Those can usually be used in combination with dataphones like Sumup, so your app fits perfectly with that combination.

Really awesome Thanks!!