The afterburner of any airplane is not in the same universe of detectability compared to a large rocket motor….. especially when the Raptor & Lightning make so much effort to ameliorate IR signature & do a great job of it.
And like any IRST system, it only works if one already knows what place to look at.
I think you are assuming a panacea where there simply is not one to be had.
Satellites will offer a scope advantage, but not a detection one.
Plus, it is an incredibly expensive way of taking a punt at hoping to catch an image in the right place at the right time.