Double rook vs queen advantage in endgame. What should I have done?

Apparently, I was winning. It didn't even remotely crossed my mind to even try to pull it off, given that I was also short on time.

But this can be useful to learn. What are white's resources in this endgame?

I assume the engine is wanting you to trade down on f5. If black obliges, its an easy win. If not, black's position is just kind of obviously miserable after you win the fpawn, although can still be hard for a human of course. Basically, in the final position black's pawns are too weak and your rooks are coordinated.

The sort of endgame I totally dread...
Any endgame with queens can get very complicated I don't think there is an easy route here for white as a human even if the cold engine says otherwise

Yep, doubling up on the f-pawn should give you the win (slowly but surely).