[reposting here, in case it helps anyone else] OBS 29.1.3, installed as much as possible from packages -- NOT snapd.
I just did this import of OBS Scenes from Windows to Linux this week, and it actually worked fine. (Using latest OBS versions available to each platform), but there's a dead-simple fix: When you're on the Import screen, AFTER you have selected your file(s), there's a tiny little check-box field that bizarrely defaults to NOT being selected on the far left of each line. (?!?)
Click that little checkbox, and your JSON file(s) will import just fine.
PREREQUISITES:
Obviously you'll need to have manually copied ALL of your source files to the new system, installed ALL your OBS plugins, and restarted OBS *BEFORE* you attempt to import anything. (I think some folks aren't doing this first.)
After the import (w/the checkboxes clicked), go into every custom Plugin's Settings menu and change any absolute paths to files. (Windows paths are not usable in Linux, obviously.)
Then, go into each Scene component, and do the same. (Ex: Text element loading from a file --> point it to the new Linux file location.)
OBS itself likes to crash about once every 24H in Ubuntu 22.04.03/Gnome/latest, and Ubuntu has *never* understood the meaning of "stable branch" (don't even start me on this topic; I've run it at Tier 1 Telcos since 10.04). But a facepalm-inducing daily cron job and start service will work around those issues.
Kick/Pyr0sa