PS Vue is limited to a few countries. As an example it isn't available in their main Sonyland market: PAL regions.
Regarding PS4, I said allow me to buy, not to play. As an example, to allow me to activate the download PS3 and Vita games from a PS4 for PS+ games as I can do from the website. When I talked about emulation (so playing) I mentioned PS5.
I agree in this case.