You could put that tutorial on github (or some wiki), so it can be fine tuned ;) If you want, we could add it here: https://gitlab.com/sovereign-individuals
And I wonder if it would make sense to have a wiki associated with SN.
If you can improve the documents, please make a PR to the repo.
Might be a bit more than that wrt card setup.
This system uses SUN authentication on the NXP 424 card. The card tap data changes on each tap and this is used to verify that you have the actual card and haven't just copied the data.
The setup of the card to achieve this is described in the documents on this repo as well.
Yes, it closes the loop, as you said.
So basically this open source code could replace the 3rd step in this guide, so that you don't have to use ln.cash and can use this instead running in your own server.
This basically closes the loop and makes everything necessary to make lightning tap payments open source, and peer-to-peer, with no need of any intermediaries.