Using Mapbox Native SDK be use without account/subscription?

I have my own vector tile server that can serve request in GeoJSON/MVT format. I'm reading somewhere in the mapbox website that I need to register for an account and inject the credentials to either Android or iOS when integrating it to my application.

Question,

  • Is it required to have a mapbox account and an active subscription (though you can have a free account) to fully use the native OpenGL SDKs? I have my own tileserver and I will be creating my own styles. I was wondering if the application will be use by a million users, what role will the subscription/account/public token play if not using Mapbox APIs (tilesets, vector tile)?
  • Is it possible to use my own data sources/styles instead of the one being provided by mapbox?