You can get any Wacom EMR stylus. These are the same ones that work with the Samsung Galaxy Note line, so if they mention compatibility for those you're good.
For example this will work:
https://www.amazon.com/STAEDTLER-180.../dp/B086N4KK7Z
The official Boox stylus does attach by magnets, I don't recall if it had an eraser. I don't think so. The magnet hold was IIRC not very good.
You don't need a screen protector. It won't break writing but it may feel different. It's possible there is one on there since they often shipped with one.