Arduino IDE Flatpak

Flatpak build of Arduino IDE. To run the app you need USB permissions, preferably, the user has to be part of the dialout group. Alternatively, add

KERNEL=="ttyUSB[0-9]*",MODE="0666"
KERNEL=="ttyACM[0-9]*",MODE="0666"

to /etc/udev/rules.d/50-arduino.rules.