Yes, the S20 is a smart plug and it can be re-flashed with your own code, including Blynk code. There’s info on re-flashing similar type of smart plugs, and some code examples here:
Cutting the power isn’t the same as using the soft power switch on the PC, but it depends what you want to use it for.
I spend quite a bit of time away from home and want my PC off during these periods. But, I also want a way of remotely powering-up the PC so that I can connect to it remotely via TeamViewer. I don’t like WoL, and it’s not reliable enough for me anyway, so this solution works very well for my needs.
Pete.