The S7 is too old. Technology changes really fast in Android devices and, in Samsung's situation, you just can't keep everything supporting every version of the OS.
I want pie with one ui for my galaxy s7 but I also don't want to root my galaxy s7 just to get android pie with one ui. WE NEED PIE WE NEED PIE WE NEED PIE FOR OUR GALAXY S7'S
You need a pie, then bake one or go to grocery store and buy it