Ask HN: Simplest way to create a simple digital currency (no blockchain)

the (elementary) school my daughter goes to wants to create a simple digital currency for the pupils. The current use cases are pretty simple:

- kids get some amount of 'money' when they enter the school, also sometimes extra money for contributing to the 'common good'

- occasionally they create 'stuff' (handicraft, etc.) during classes and they can sell it to each other on school fairs

- there should be some way of managing the 'wallet' without having access to a smartphone -- the younger ones might get a QR code or a PIN and that could serve as the 'wallet' during fairs

- censorship resistance is not needed, nation states don't want to break into the network (likely)

Is there anything that already supports this extremely simple use case? I think something could be done with e.g. Google Sheets + AppMaker or something similar. Any other ideas, thoughts?