It started as a survey
The best point-of-sale ideas are already written down, in the open, across projects with tens of thousands of stars between them — ERPNext's stock ledger, Open Source Point of Sale's drawer discipline, BTCPay's tender model, URY's floor plan, TailPOS's offline-first instinct.
They are also written in PHP, Python, C#, Dart, Vue and C++, under MIT, GPL and AGPL. You cannot staple them together into one product. So HBB POS took the idea each one is best at and rebuilt it in a single browser application — and put the credit on a screen inside the app, where it stays visible.