Yes, use Magisk.
Flash it through TWRP Recovery.
Then in Magisk Manager install the MagiskHide Props Config addon then you can also spoof your device as a Google Certified device like Xiaomi Mi or Nvidia Shield and more apps will work.
Make sure the 2 Safetynet tests pass in Magisk Manager, then you are good to go.
If Magisk is working, you can also delete the /system/xbin/su file since Magisk handles the rooting and hiding of root now.
The Magisk Zip is in the 2 firmwares opening posts.
Copy it to a flash drive or external hard-drive if it’s not picked up in internal storage.
Then you just flash this zip through TWRP.
You will see a new Magisk Manager app in Android and need to follow the setup to install it.
You can then use Magisk Hide in Magisk Manager’s settings, to hide root for your app.
If your app requires Google Certified device checks, need to pass Safetynet, you can download the Magisk Hide Props addon and follow the instructions to spoof your device as something else.
My AndroidTV firmwares also have another menu where you can flash the patched Magisk boot images directly from Android and you don’t need to use TWRP Recovery.
But I need to update the instructions a little and post screenshots for people to use it easier.
If you use a class 10 or higher speed microsd card, Android actually works fine and you don’t need to use the emmc. It’s easier to remove the micro-sd card each time to try new firmware.
You can also use SDDiskTool to make the rkupdate format firmware a bootable micro-sd card to transplant onto your emmc without a PC or removing the emmc but firmwares need stock recovery and not twrp recovery for it to work. I’ll try to ask Radxa to check this since it’s something I just recently noticed.
For a micro-sd card, you use the gpt format firmware images and use etcher to flash it.
While etcher is flashing it to a micro-sd card(you need a card reader for your PC) it will display the write speed of your micro-sd card. Anything over 12MB/s will work well, my old micro-sd card was only 8MB/s but the new 32GB one is 18MB/s write speed and it boots much faster.