... So... am I SOL on mileage earning for this flight? ...
No, because NH does not use R for Premium Economy
...Anyone know the ANA equivalent to UA's "R" fare class? ...
It will likely be NH's N fare class
Only way to know for sure is to give NH a call.
BTW, NH has three premium economy fare class G, E and the lowest N.
Are you crediting to NH or UA?