Well i wouldn't be so sure Niko.
The issue is the amlogic s812 chip used by the t8s plus and other box suppliers' machines.
As far as I know Amlogic have not released a SDK (software development kit) for the s812 which would technically allow a marshmallow firmware to be developed. That is a pre-requisite for all other suppliers as well as Droidbox.
Things are different for the s9xx chips used on newer boxes like your cheap "q" box, the droidboxt8s plus v2 and imxqpro v2.