If you don't have an app in the app store, but instead direct people to your web page, you can bypass the app store based tracking and compliance issues. Gab does not have an 'app' for this reason.

Gab claims to have their own servers (the actual physical hardware) which would bypass AWS, Azure, Google Cloud etc. After all, the 'cloud' is just server space you're renting from someone else (in a general sense). Gab is running a Mastadon fork on their own hardware.