Going into this weekend, Royer was only underperforming his xG by 1.19. That's second-worst on the team (behind Adams), but it's a lot better than players like Almiron (4.82), Ola Kamara (2.34), Zardes (1.88), Elis (3.87), and Giovinco (3.95).
I think shot volume might be playing a role in those numbers, the more shots you take the more volatile your G to xG stat will be. Giovinco and Almiron shoot on sight, they have more shots than anyone else in the league by a ridiculous margin. Zardes and Elis are in the top 10 as well. Royer on the other hand doesn't tend to pull the trigger unless he's almost in the six yard box.
I could be letting the eye test fail me here, but I can't really recall many of his goals that I'd consider clinical finishing. Last summer he went through a stretch where he did start shooting more regularly from distance and the goals were pouring in, but even a lot of those were deflections/keeper errors.
He still works his ass off enough that it's not a crazy idea to give him a run at striker, especially when Etienne, White, and Abang are the alternatives.