Caveats? Little of the networking works (yet), and you'll need a degree in the hacking black arts to follow the instructions below and do this on your own Lumia 950 XL (summary: just don't).
From the MSPU story:
He describes the procedure as such:
1) WPInternals 2.4 to unlock bootmgfw
2) 1st shim: github.com/imbushuo/boot-…
3) Kickstarter: github.com/imbushuo/lk (msm8994-test-2 branch)
4) UEFI: github.com/imbushuo/Lumia… (Get Linaro toolchain and EDK2 ready)
You can find more detail at Ben’s Github repository, but don't get too excited - by the time Ben and others get this hack working and in user-installable form, so the end of 2018, we'll have a Surface Mobile for sale, I suspect. Admittedly, the latter will cost you £1000 and the former is free, but hey....(!)
Anyway, certainly a link of interest!