Don't get me wrong as i am not saying it won't run.
Hell i have matrix 19 running on older S812 and up.
I am just saying that if your not self sufficient in developing and are like most that rely on other developers for firmware then even a free box without current software really is not worth anything other then a parts board to be played with or thrown on to your pile of old devices.
Out of all the different developers out there to a large extent they all are based on OE and LE and as such pretty much make use of the same build system that each fork has altered for their own purposes and the amount of support for the older boxes is getting smaller all the time.
Currently with LE focused on moving linux to mainstream and off the old proprietary BSP's and help push Kodi thru the python 3 upgrade they have chosen to support a smaller pool of devices while transistioning... So most of the other Distributions are trying to support some of the older devices while still supporting the older propriatary BSP's for the devices they have chosen to support.
All I was saying was that unless your willing to learn or already have the ability that you will probably have to either rely on someone else's firmware and if you can't find any then you will be at least at a minimal level have to take some existing build and hope to mod it enough to get it to work. Maybe just a dtb change maybe more...
So as much as $15 bucks is a good deal you may not have much of a choice other then running Android and then Kodi as a app, which to me is something not worth the effort.
I have been running Linux on these devices going all the way back to the Dream devices as the idea of running Kodi on a OS that is basically a touch screen OS is just dumb in my opinion if your trying to get the best performance out of Kodi. but hey to each their own...
But just to be clear i never said it can't or won't run.