Hello LMH17061,
I know you aimed your question to Rich, but the following may help.
I also wish I knew why I couldn't import directly from the camera. I suspect it's related to Panasonic's apparent assumption that the computer involved will be a Windows machine. ! I wasted an hour or two fussing with this issue!
I finally found that the only way I could move the video from the Panasonic HC-V180 camera to iMovie was to remove the memory card and use an adapter (such as: https://www.amazon.com/gp/product/B08C2BBLSJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1) to connect it a USB port on my Mac Mini.
The memory card did NOT appear under the list of DEVICES on the iMovie Import screen. It appears under CAMERAS, as "HC-V180."
Then, it took a while to realize the video files were in a folder labeled DCIM and in a sub-folder labeled 105YAPHH. Neither of them looked like the right place when I first saw them. I'm not sure those are always the labels, so you may need to open all the files on the card to find the MP4 video, assuming you set the camera to generate MP4 files.
(Although a post on Apple Discussions says iMovie accepts the camera's AVCHD files, I've never tried that.)
Let me know if that leaves you with questions!
Dick