Don’t use the stock kernel. Use the HWE one if you want newer hardware to work on Ubuntu and its derivatives like Mint.

Or try a Fedora live-usb and see if it works with the newer kernels.

My newer hardware is circa 2015.

Is your 2 in 1 one of those baytrail cpus with some atom z sonething? If so, they're really problematic with linux, since they were released, due to some obscure stuff in their soc. I remember even people who formatted and reinstalled windows losing functionality.

HP Elite x2 1012 G1. Has an Intel Core M5 processor.

Frankly. I was expecting to spend hours getting this thing in a useable state, but Mint had everything working on a clean install except for the the volume button on the tablet itself and the function buttons on the KB. Honestly very impressed. If I did a clean windows install I would be pulling drivers from HP and installing them for about an hour to get this level of functionality.

I figure a quick script or something that turns on the On Screen KB when the physical KB isn't detected is possible, and that I can manually config the volume buttons and keyboard shortcuts. Then this tablet will have all its features working.