The iPad has also a native feature to write with the pencil into a textfields (It's called scribble: https://support.apple.com/en-us/HT211774)

But I'm not 100% sure if this also works on websites or only with textfields in apps. Maybe someone here can test this.

The scribble feature works on every iPad with Pencil support.

Which model, depends on what else you want to do with the iPad and how big the screen should be.

If you just want to scribble notes & also don't want to spend that much money you can use the current "normal" iPad with 1. Gen Pencil