Honestly i do not think your gonna like doing this. If you whole thing is having a tablet with its battery life etc then de-googled android is probably gonna be better for you. Android is based on linux anyway and custom ROMs exist to give you a more privacy focused and in your control OS. Like Graphene OS for example.
If you want linux and a tablet id instead recommend a really slim thin and light 2 in 1. Maybe with detachable keyboard. These are typically made with x86 Chips instead of ARM tho so the battery life wont be as good.
AMD has a similar technology tho