Btw, have you guys heard of Taler? It’s pretty interesting and I think you will be able to use it with a libre app
NGI TALER is a pilot funded by the European Commission and the Swiss State with the very concrete objective to roll out a new, best-in-class electronic payment system that benefits everyone: people, merchants, banks, financial authorities, auditors and anti-corruption researchers. The project doesn’t have to start from scratch either, but builds on the strong foundations of GNU Taler — the privacy-preserving digital payment system developed by the GNU community and Taler Systems SA with support from the NGI initiative. This offers privacy for those that make payments, while enforcing transparency on those that sell. By providing micro payments at very low overhead, GNU Taler permits internet business models to shift away from advertising revenue or subscription models, especially for online publishers. No-risk transactions can lower transaction fees and open online payments for the underbanked population and citizens marginalized from digitalisation.