Ha, so this or PS3 emulation....

One thing bad, the ps4 controllers touchpad doesn't work correctly. It controls the mouse cursor in Linux but won't work in game.

I just tested, I installed it easily with Lutris, no necessary tweak, just click install, launch the app (you need a Sony login or subsribe an account).
I played several PS2/PS3 games:
Dead or Alive 5, shadow of the Colossus, Zen Pinball (not playable because of the latency), Red Redemption...Finally it's Sony that launched the games streaming battle. A lot of PS2/PS3 games are available.
Sony took a step ahead of its main competitors Nintendo, Microsoft, Valve...
One more thing, you can play with a x360 gamepad.

It it's only a streaming platform Sony could well develop it for Linux too. At the end of the day Microsoft is also their enemy.

Do you need an official PS controller to use it or could be others good also?

wvstolzingThis is likely a weird question, but do you know anything regarding the following type of scenario?

I used to have a PS4, in fact I bought a digital copy of the 'remastered' The Last of Us, and finished it on the device. If I were to get a new subscription to PS Now, would I be able to stream The Last of Us from my existing library to my desktop? (I suppose my 'PS4 library' still exists intact; if I were to get a PS4 again, I should be able to have access to the digital only games that I bought -- or so I think.)

I doubt it, however maybe there is a KB article about that question on an official Playstation site somewhere.

What I was going to bring up about this is remote play. There used to be (still is I think) a way to stream your games from your own PS4 console to another device, be it Windows or Vita. I have done it with both of those devices in the past. So, you'd need to obtain a PS4 to get access to your digital library again, and then you could probably do that remote play on your LAN. The way I understand the PS Now service is as an independent subscription where you can play any game in their library any time, just like a Spotify subscription but for games instead. So, you wouldn't have to buy any specific games with that subscription.