Can't install do different drive after first installation
After installing RetroDECK on my steam deck, I received my new Micro SD card, which I want to install RetroDECK onto. But I couldn't find a way to change it to a new drive. I (idiot) didn't know there was an uninstall option on Discover. So I deleted the files and then tried reinstalling RetroDECK (when I discovered Discover's uninstall feature).
So I uninstalled it and then reinstalled it again. Still, the drive selection screen on the first installation didn't appear. I looked into the "retrodeck" folder to find it empty. Now there is no way for me to put my ROMs into RetroDECK, which means I can't use it. Is there anything you can do to fix this issue? Or am I missing a simple solution?

You could do a flatpak run net.retrodeck.retrodeck --reset to call the initial setup again but that will be ereasing all your custom configurations if you had any.
In the next version there will be a tool to move the roms folder.
It also seems like the lockfile is not being removed at uninstallation.
It also seems like the lockfile is not being removed at uninstallation.
No, as there is no "uninstall commands" for Flatpak. Not that I am aware at list. However I am deprecating the lockfile little by little.
The migration tool has been integrated into the Configurator so this issue should be resolved.