If you want true POS capability you’ll want to find the right POS solution that integrates to Airtable (usually via Zapier) I’d be glad work this through with you. You want to leverage as much “off the shelf” capability as possible.
Also have some experience with linking airtable in innovative ways with some of the top cloud based and API enabled POS’s out there so please let us know if there is anything we can help with.
Actually I now have an in house programmer who works with airtable API. We have developed software that linkks lightspeed POS to our airtable bases. we have very complex inventory management needs and we do consignment and used product purchasing in large quantities, plus managing new product catalogs, so we do all of that in airtable and then we can create products in lightspeed via api from the data we have already entered in airtable. User databases too. Very fun!