I updated my NitroPad v54 in-place with no issues. I’m running coreboot + EDK-II. I believe it is basically the same machine as the NovaCustom V54. I would just advise to monitor the upgrade as you’re doing it. I left it to have lunch and came back to a black screen and had to reboot and start over.
However since running R4.3 I’ve encountered this bug which, right now, is rendering my machine almost unusable: Unrecoverable GUI bug on R4.3 on NitroPad v54