Imagine you own a shop, and are clueless about IT. You don’t even have a till never mind a credit card machine. You only have an iPad. You rent floor space to people who put their stuff in to be sold, and you take commission on the sales. You also do commissioned pieces yourself for direct customers.

Is there some kind of ready made Google type solution for keeping track of all this? Or does one simply use a spreadsheet in Google sheets?

http://www.computerworlduk.com/galleries/it-business/8-best-free-open-source-inventory-management-systems-3627300/

A start

But TBH, your MVP is probably a few linked sheets, especially if volumes are low and you only want to use an iPad

Using Sheets, could someone such as myself create templates in sheets then lock the relevant bits and add macros and whatnot to make a tool out of it? I mean, like I could in Excel? To hand over to the people running the shop..

Stoner is your man for this, but I’d expect you could do all the above.