FYI you can create symbolic links on Windows 10 and 11 as well. I tested my theory on Windows with the non portable Joplin, and I'm able to make the profile portable and run from a usb drive. So I suspect it will work on Linux as well.
I created a folder called joplin-desktop at the root of my usb drive and then ran the following command from command line (running as administrator) to make a soft link:
mklink /D C:\Users\<user>\.config\joplin-desktop E:\joplin-desktop
Then the data is created on the usb drive. If I start Joplin with the usb drive unplugged, it will throw an error and wont start up, but then plug in the usb drive and try again and all is good.
Note that if you want the backups to go to your usb drive as well, you will need to make a soft link for that as well (and the same applies for any directories used by plugins):
mklink /D C:\Users\<user>\JoplinBackup E:\JoplinBackup
And also if you use the new secondary instance feature of Joplin, you will need to make a soft link for the folder which is created under C:\Users\<user>\.config for that