Keep in mind that the package is not official, there may be bugs specific to the flatpak. If you find such, report them here.

Note: This is osu!(lazer) - a future update which is yet to be considered mainstream. It is not osu!(stable).

Check ~/.var/app/sh.ppy.osu/data/osu

osu! uses OpenTabletDriver for graphics tablets support.
However, it may not work for some reasons, here are some of them:

• At the moment, the tablet is controlled by the kernel module
  You need to unload the module yourself from the terminal, using the following command:
  sudo rmmod wacom || sudo rmmod hid_uclogic
• Failed to open device streams
  You need to download and execute the script from this repository (tablet-udev-gen-rules.sh) and create some udev rules
  Don't forget to install git and jq via your package manager!
  
  If you are not sure/do not understand what to do:

curl -L -o ./tablet-udev-gen-rules.sh https://raw.githubusercontent.com/flathub/sh.ppy.osu/master/tablet-udev-gen-rules.sh
chmod  x ./tablet-udev-gen-rules.sh
./tablet-udev-gen-rules.sh --idk # press Enter after udev question

or, follow this guide

Note: To generate udev rules using the official guide, you need to install dotnet from the repositories of your distribution

Please, share your experience of using a graphics tablet in osu!. Both on the build in flatpak and on the official one (AppImage).

This happens because when a flatpak container is launched, only the necessary directories are passed through to it.

If you want to be able to access all files and directories in your home directory, use Flatseal from flatpak, or sudo flatpak override sh.ppy.osu --filesystem=home