So if I have iap subscriptions not related to the products I want to sell through Stripe, that affects the 30% cut of the products as well?
Yes. So am I allowed to use Stripe for this?
You can use whatever payment processor you want, but if you ship it on the App Store with in-app purchases, then Apple will demand a cut. This happened to a few dating apps in the Netherlands that implimented a similar workaround but still got invoiced for 30% of their IAPs.