The bootloaders have been locked; and the 2015 models (iirc) were the last ones where a bug allowed unlocking them by shorting some pins. Without an unlocked bootloader, you might be able to root Android, but you can't replace Android or the ROM.
Not that it matters anyway - it's MediaTek. Their partition layout and driver model from those eras is generally a disaster. There's no way you'd be able to make FrameOS in a reasonably elegant way work on that hardware.
Not that it matters anyway - it's MediaTek. Their partition layout and driver model from those eras is generally a disaster. There's no way you'd be able to make FrameOS in a reasonably elegant way work on that hardware.