You can be sure that even the Epic version will still require the Ubisoft launcher. That is how all of my Steam purchased Ubisoft games are with the exception of the first Assassin’s Creed which predated the Ubisoft launcher. All of the others require it regardless of how I bought it.
I’m going to wait for at least two or more years after release for the new Prince of Persia. My days of paying full price for Ubisoft’s games are over and recent statements from the CEO make me reluctant to ever buy their games again.
You only need a key to activate Windows. Windows 10 and later will install and run just fine without activation.