This is a spin off from another question. I recently got a 2018 15 MBP with Big Sur on it. I erased the disk and installed High Sierra as I need to run some old software. The install seemed to go fine but a curious extra volume appeared on the Desktop after the install called 'Update' which seems to contain NVRAM and firmware related files.
The volume is mounted normally and not hidden.
I can find virtually no reference to this happening online anywhere.
My guess is it is created as some sort of temporary volume to do with the installation and it should not be there afterwards?
I followed Apple's instructions about erasing an APFS disk prior to installing High Sierra, but these instructions seemed incomplete in hindsight as they suggest just erasing Macintosh HD if other partitions are not available. As I was new to APFS and its partition scheme, it seemed later a better thing to have done was 'Show devices and then erase the device at the top of the hierarchy and I wonder if what I did helped created this mysterious Update volume ?
Anyway what is this volume and can it be safely deleted ?