Hi @sadielcuentas,
I don't know if there are alsa drivers for ARM architectures, but the Linux kernel used by Andronix won't be able to use them anyway. You have to install the Ubuntu Studio audio package: sudo apt-get install ubuntustudio-audio
After that in Pure Data choose "portaudio" in the Media menu. It should default to pulseaudio. Also make sure you have started pulseaudio in the terminal before starting Ubuntu: pulseaudio --start
This version of Linux is very limited with which audio software you can use, anything that relies on Jack or ALSA won't work. So no Audacity or Ardour. But I have gotten Pd, Cecilia, LMMS, REAPER and Processing working so far, among others.

I don't know if you figured this out or not. For me Pd-l20rk was not on the MacOS list of applications with permission to access the microphone. Pd-l20rk did not prompt for microphone access for whatever reason. Since I'm on a university machine, my only choice was to open Pd-l2ork via the command line. This worked but now the only way to ensure microphone permissions is to open it via Terminal.
I put the direct path to the executable in the command line:

/Applications/Pd-L2Ork.app/Contents/MacOS/nwjs

@sadielcuentas I don't know if you figured this out yet. I was able to get Pd to work using Andronix with Ubuntu 20.0.4. At first it didn't work as you documented. However, after I ended up installing ubuntustudio-audio it ended up working.
I had to choose "portaudio" in the Media menu then it saw pulse audio as the output. I can only get sound out at the moment. I don't know if input is even an option but at least it works somewhat.
I hope this helps someone.