I have a huge library of VR180 videos which need trimming, joining etc. I can do this with the windows version of Bandicut and but find it hard to select the ideal edit points while viewing VR content on a 2D monitor.

Due to the high resolution and bandwidth required for VR180 videos, any editing that requires re-encoding becomes extremely time consuming and results in loss of detail. I love Bandictut's fast, lossless mode for this reason

I thought how nice it would be to be able to perform these edits from within my VR headset but could not find anything suitable.

So my suggestions are:
Develop a PCVR app that will allow direct editing of PC files from within the Quest or other PCVR headsets
Develop a quest app that will run on Meta Quest headsets, that can edit files shared via SMB
Develop a display extension for windows based bandicut that will allow VR headsets to be used as a secondary display. (Premiere Pro used to do this.)

Fingers crossed!