System - Fedora, VSCode, Platformio core 3.6.5, Platformio home 2.0.0
If I click on Open Project I get a menu with Places and Devices. One of the places is Projects. This works as expected. Another place shown is my user home directory. If I want a project from a subdirectory there is no way to input that. Clicking on /home/my-user starts a spinner going and the dialog says loading. This continues until I close the window. Similarly if I want to import an Arduino project from /home/my-user/Arduino, there is no way to specify the Arduino directory. I just get the spinner. There does seem to be a way to add a place to the Projects menu.
In summary it seems impossible open/import a project that is not already in the Projects directory.