HEVC is supported in the latest beta version, if your computer has a hardware HEVC decoder. It's a WIP as HEVC support was just recently introduced into Chromium (source: author)

LosslessCut does work with HEVC, but the GUI doesn't support playing them so it generates a low-res H.264 video to use as a stand-in for previewing and then does the actual cuts on the real file.

I mostly use it for cutting up clips from an older GoPro so I don't run in to this often but I did borrow a Hero9 recently and it worked fine, it just was a bit less streamlined.

I’m not sure whether this linked on does or doesn’t handle HEVC.

But Avidemux in copy mode should handle it, I’ve been using it for a while in a similar lossless manner to this tool and it’s great.