If they are considering applying duty/rest rules, that's for the safety of people on the ground, not because large UAS flying resembles manned aircraft flying.
The FAA is staffed by pilots and bureaucrats, neither of which has any incentive to stick their necks out and propose risky rule changes to favor UAS operators.
If anything like that is going to happen, the UAS community will have to lobby and advocate for it. The industry stakeholders (airlines, ALPA, flight schools) will probably have to concur to the NPRM (or at least not protest). Nobody is going to just hand it out (well maybe if the pilot shortage gets REALLY bad in ten years).
Personally I think a *little* credit might be appropriate, but not a lot of credit. Flight engineers are exposed to a jet cockpit and crew environment so they get some benefit from OJT. Like with helo pilots, the real concern is if things get ugly during landing, you need the right instincts because you might not be able to think it through.