It's doesn't matter if it's has a small FoV but whether it has the range or ability to provide firing solution which modern IRST have. small FoV problem can be overcome using more networked drones. my whole point being using passive sensors as much as possible as they have the least amount of chance being detected even by stealth planes. Imagine a strike package of mirage 2000, sukhoi ,MIG 29 going up against a sqrdn of F-35....what will you do?
a mix of such small stealth drones flying 100 of km in front using jammers, active and passive sensors will detect F 35 long before F 35 mange to detect them or strike package. They will instantly relay information back to sukhoi to fire there longer range SFDRs.
It will be over for F 35 by the time it sensors detect the drones or incoming barrage of BVRAAM. best it can do is turn and run.