This is an interesting development, since FSR is open source, developers are expanding where it can be used. Here it is very much helpful for Steam users and VR, basically any game that uses Openvr as in most VR games on Steam can have FSR. Guy in video explains it but I had to take a double take on the image differences while he was bragging about basically the frame times going down tremendously, which it does. Could be very useful for very high resolution HMDs and lower end systems.
https://github.com/fholger/openvr_fsr
https://github.com/fholger/openvr_fsr