Luckily H.264 10bit is rare. It's also clear that this is a hardware limitation.
Have seen H.265 10bit Never come across H264 10bit
The problem is, although Hi10p has always been in the H264 specs, since no one uses it in the commercial space, hardware manufacturers never implemented it.
Why would they build hardware specs no one uses?
H264 Hi10p is to my understanding mostly used for anime. Or at least some subbing groupe used it.
Why? because it reduces encoding banding , and anime encoding is very prone to banding.
But since these applications are not commercial ones or are even labeled as illegal ones, why would they now create hardware decoding for that purpose?