Rooting/Hacking Hisense A6 M7322 Based Android TV

I have 2 of these with Android 9. A 50 and a 60. They use the android home launcher and so display ads, etc.

Specs:
Mstar M7322
2gb Ram
4GB storage
Mali GPU

Right now:

Adb can be entered over wireless. Most apps can be user disabled/uninstalled.
You can use termux with ADB addon to use ADB right from the TV with BT keyboard.
USB is disabled when ADB runs.
Android launcher contains the input switcher so hard to replace but this one works: https://forum.xda-developers.com/t/app-android-tv-projectivy-launcher.4436549/
Can only use VPN based firewall. Can't use my VPN.
Can't be trusted on network.
Remote has a microphone (hi Orwell!).
Bromite/VLC/Kodi/etc all run.
No 4k@60 4:4:4 beyond 8bit.

Issues:

* No USB adb access. What kind of male to male cable do you need? Does it really work?
* There is no service jack/socket or service manual I could find to get the bootloader console.
* On reddit someone used a raspi zero?

* Cannot list partitions on ADB
* Supposedly unlockable from bootloader/fastboot but beware:
https://forum.xda-developers.com/t/android-tv-stuck-on-black-bootloader.3803695/
* No firmware updates to dissect.

Has anyone gotten any farther with this or any other mstar based TVs? Tried more malwareish programs like kingroot? What's worth trying next?
If the bootloader can be unlocked a backup could be made and it might just be a matter of adding magisk binary for all of that receiver/service disabling goodness.
I would love to try an AOSP rom.