@Goochman did you test/implement the instructions you posted? I like the idea of installing M.2 SSD, setting boot order so that M.2 SSD is booted first, and installing boot selector directly on the M.2 SSD. Every boot asks which OS, no need for a thumbdrive plugin/unplug (typically slower and less stable than internal M.2 SSD), and no need to edit BIOS every time you want to switch. All of those methods are valid, but I think this is most stable and least work every time you want to switch.
If someone were to put linux and windows on the M.2 drive, anyone have any suggestions on a drive and partition size and why? Windows 10 seems to have been done by several, is Windows 11 also good on this hardware?