With some creativity: create a PDF file on your computer to serve as your “empty notebook” with required backgrounds, which you then write on top of on the RM2
With some creativity + light hacking: create your own custom template PNG file with the darker lines on your computer and transfer it to your device via SSH. You can make it appear in the template selection screen. There’s other posts on this subreddit which detail the process. I think it still comes with a caveat that custom templates need to be reinstalled after each software update.
There’s 2 options as far as I know: