Google (used to) scrapes the specific details authorized by robots.txt and uses it to make your content visible.
OpenAI scrapes everything it can technically see, ignoring robots.txt and feeds i to a black box and regurgitates it claiming it’s something new, that it deserves to be paid for.
Quite different actually.
I would recommend Shopifys APIs. Theres a lot to them, they’re well documented, and you can build a developers store for free.
Adobe commerce is another one. You can get a dockerized store up and running pretty quickly, also free and their documentation includes some basic suggested workflows.
Edit: these are mostly for practicing consuming apis, not sure if thats what you were looking for.