The TS-X77-R rack-models have had later generation Ryzens for a long time and so far the released special Hero edition models are only available in rack form factor. For the desktop TS-X77-models (that is what the OP ask about) they're still holding the release of the upgraded models back. We all understand that it will come, the only question is on what event Qnap choose to do the official announcement.
Unless you as a customer have extreme CPU demands it's kind of academic though as the first generation Ryzen series will still outpace almost all other NASes on CPU resources available. When you have too much CPU, it doesn't really matter if it's 2 times or 4 times too much.