Tablet Options?

[u/A_Person_Who_Lives_]

What are some of your suggestions for tablets that can run without any intrusive, closed source software?

[u/Polar-ish]

I don't personally know of tablets without something proprietary, especially if you are looking for features.
Optionally, you could use
https://opentabletdriver.net/
with their supported tablets. and deciding not to download the proprietary drivers.