As I have been informed by the OpenGL team, 10-bit color per channel is supported for both AMD consumer and workstation products.
It can be enabled by"10-Bit Pixel Format" option available in the Radeon settings panel [Radeon settings->"Graphics" Tab -> "Advanced" options -> "10-Bit Pixel Format" (“disabled” by default )].
You can try it and let us know if you face any issues.
Thanks.