The best way to get the Stalker 3.0 scans is to collect stalker deathmarks as usual, be eligible to even make this version spawn (meaning having done JADE SHADOWS mini-quest) and then do some of these Operation Alerts on the Steelpath difficulty with people who have also these conditions met ( Stalker deathmark actif plus Quest done ) . If the stalker then spawns there, he would be 100% to do so as this new Protector Stalker, at least as long as the event runs.
I thought these scans would be a nightmare to get, as most people already tried the "help as Stalker from relay option" and then be done with that nonsense. So you would hardly ever have one of these new Stalkers in your PUB squads the longer the event was already running. But no, this way I had these scans in under an hour.
https://imgur.com/a/uD3BJFv