As you know, the version of the Arduino IDE packaged in Debian is quite old, even in unstable. It is possible to download the version from arduino.cc but then we have to manually handle the updates.
Another solution is to use the flatpak version of Arduino, available on flathub : https://flathub.org/apps/details/cc.arduino.arduinoide . The issue here is that the Teensyduino installer does not handle this kind of installation. With this setup, I've tried to copy some of teensyduino files (in the hardware/tools directory) in my $HOME/Arduino directory. And it kinda works. The program is compiled, only the call to teensy loader fails.

I think it should be possible to have a teensyduino installation compatible with this arduino ide setup. One of the big advantage is also that we don't need root privilege at any step.

What do you think ? Is it something you wanna do ?