PS4 optical out should be able to output 5.1. I'm talking about the optical out on TV which probably depending on the manufacturer, some might just pass through the original audio, some just push 2 channel sound that is supposed to be played by the TV speaker for the optical out (which is annoyingly stupid... Why have optical out in the first place?).
At least now you have a set of matching speakers. Next step is to actually buy a receiver [emoji4]
Edit: basically if your TV have an optical out port and can actually output 5.1, then this home theater is a good solution to get surround from PS4 and PC (and other devices connected to the TV HDMI port) without having to buy a receiver.