I didn’t see any mention on whether there’s an upper limit on the number of subscription groups an app can offer. Is there an upper limit? To be compliant with 3.1.1 and 3.1.3(b), I would need tens of thousands of subscriptions groups.
There is a limit of 10,000 IAPs per app.
There are a few apps, including one of mine, that have thousands of IAPs. I don't know if this applies to subscriptions in the same way that it applies to non-consumable purchases. The docs don't seem to distinguish between subscriptions and other IAPs so I guess it does.
You can create up to 10,000 in-app purchase products per app.