Today 10 bits are available for a small number of devices that support Hevc Main10Hdr10. These are Sony Xperia 1/5 / 1II / 5II, LG from V35, Samsung S10 / S20 (Snapdragon), Xiaomi Mi9 / Mi9T / Mi9 Pro / Mi9T Pro (but only Rec709). Perhaps there are others, but now it is difficult to remember them all. Also 10 bits video recording can be limited to 3840×2160 resolution.
We observed that on Mi9T and other Xiaomi devices with a processor lower than Snapdragon 855 10 bits are available only up to 10 Android. More often on the 9th.