Aurelio

No, is not. 
If you remove usb device, it will boot android. 
If put back usb, go to linux. 

@Aurelio
Indeed, it was indeed the fork image of Armbian.
I tested with this image: Armbian_23.02.2_Aml-s9xx-box_bullseye_current_6.1.11.img.xz that you recommend and it starts correctly on Armbian now 👍
 
Thank you very much for taking the time to answer me 😃

These boxes are 1G/8G if you're lucky, some only have 4GB of storage. You can boot standard Armbian kernel 6.1 community builds. Just put them on a USB stick and change the bootloader and DTB as described elsewhere. I use the s905x-p201 DTB with this box.

I found the easiest way to boot from Android into Armbian is to create an empty zip file on the USB drive, then open the Update app in Android, select the zip file and run update. It will now forever boot Armbian as long as there is a bootable USB stick

Don't install these Armbian builds on eMMC. You will brick your device and need to restore Android using USB Burning Tool. If you do, make sure you use the right image. There are at least 3 versions of this Q96max box!
 
If you want to install Armbian to eMMC, use a S905X image with kernel 5.x from here: https://github.com/ophub/amlogic-s9xxx-armbian - their eMMC installer actually works. Their 6.1 images don't boot.
 
 

@Aurelio: Yes I used method described in the youtube video above.
 
You will need serial cable connection to the PCB and adb.
The 4 pin connector on the PCB is used for the serial connection. Cheap USB<->Serial converter can be used, note the voltage level of the signals is 3V3 (only GND, RX and TX pins are needed), serial speed is 115200 bps.
 
I can't say much about the performance compared to RPi. Since the armbian filesystem is on USB 2.0 flash the file operations are rather slow. I successfully installed OctoPrint with web camera support and it seems to fork fine.
 
I still not try to write the image to internal eMMC, I want to be able to backup the stock android and have a method to restore it if needed. For now I backed up the eMMC content with
dd if=/dev/mmcblk1 iflag=fullblock oflag=direct bs=512k | gzip > tvbox-backup.img.gz but I'm not sure if this file is useful.
 
Edit:
armbianmonitor result

Vendor making false claims/advertisements about speed, memory...

Funny. Reading the datasheet of the S905L2 SoC it seem it supports only 4GB of memory. So once again a scam box.