I would like to build a HTPC for playing Ultra HD Blu-ray on TV.
As I know that Intel's Kaby-Lake could do this with it's internal GPU and chipsets that support HDCP 2.2
Does Ryzen APUs supporting Ultra HD Blu-ray play back?
I would buy Ryzen rather than Kaby-Lake indeed.
I don't know if this will help answer your question. But it does concern AMD APUs and HDCP 2.2 which is needed to run HD4K: AMD Plans PlayReady 3.0 Support for Polaris and Vega based GPUs in 2018, Vega APUs in Q2 and this thread from Tom's Hardware that happens to mentioned the same link from above.AMD Ryzen 2400G HTPC - CPUs - Tom's Hardware