Is there AMD graphic cards supporting LTTPR available in the market?
According to this Website on LTTPR it isn't the GPU card or source that produces the LTTPR signal rather it is a dock with LTTPR that you connect to the GPU card Display Port and to the Monitor: Introduction to DisplayPort LTTPR
Here is one Dock that support LTTPR from above link:
It seems as long as the GPU Card has DP version 1.4 it should work. So you need to find a AMD GPU card with an output of DP 1.4 and then connect it to something similar from above website.
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