As someone with an insight into the complexities of retrofitting certified avionics hardware and the associated wiring, controllers and antennae to fighter jets and other military aircraft, I would be completely unsurprised if, as seems to be evident from the video imbedded at #1112, the USA’s elite, pre-eminent military aerobatics team uses a portable ADS-B unit velcro’ed to the aircraft’s glare shield. And if it’s OK for them, I can’t see why it wouldn’t be OK for the PAT helicopters and I wouldn’t be surprised if that’s the ADS-B to which various references having been made.
I suppose the operational question is whether the aircraft on which these portable units are used are permitted to fly without them on board and working. My guess is that there will be no prohibition. They are just ‘nice to haves’ but not essential for the ops in which they engage.
And there’s a causal question anyway: Would a functioning ADS-B system – portable or otherwise - on the PAT helo have made any difference? The answer depends on the variables around the alert suppression parameters in each aircraft’s systems and the effectiveness of the format of alerts – if any – given in each cockpit.