Do you have a copy of the current firmware image for your box that you have verified actually works?
I have an Android 7.1.2 firmware that seems to install without issue to a variety of S905x boxes, with both 1G and 2G RAM. I can’t speak to the quality of this version of Android as I have no use for it for0 anything other than the bootloader. That said, the bootloader from this image has allowed myself and others to install NG builds to S905x devices without all the random hiccups an Android 6 bootloader seemed to present.
As I’ve said, you’d be foolish to install this ROM if you don’t have an original firmware for your device that you know already works, just in case something goes sideways. You’ll need to use the AML USB Burning Tool to flash the firmware so you’ll need to be comfortable using that as well.
As updating versions of Android is well outside the scope of CE support, I wouldn’t expect anything in the way of support from the DEVs if the flashing process goes poorly. That said, if none of the above frightens you and you’re brave enough to give it a go, shoot me a PM and I can give you a link to the firmware I’ve used.