I just installed Joplin (2.1.9) on my laptop (Linux Mint). No problem, everything works.
Then I copied my CSS + settings.json files and pasted them directly into the Joplin config folder in Linux. Great! No need to redo all the configuration, everything was set up. Pleasant surprise.
So my question (for the future) is: was it possible to do the same thing with the plugins? copy/paste the plugins folder?
(I hesitated... and I didn't dare. I didn't want to screw up my installation).