Most 45c-clearanced-frames will work fine with 27.5×2.1″

Oval rings have to be timed with your leg-stroke to have any (if there is any…) effect. In a Pinion gearbox there’s a whole set of gears (aka ratios) between the cranks (input, aka your legs…) and the belt pulley/chain ring (output). So yeah, technically an oval chainring or belt pulley can be made, but it makes no sense at all.

“Need”? That’s probably accurate.
But who around here only considers what they ‘need’ related to bikes versus what they ‘want’?
And also, 700x50s as well as 27.5×2.1s are totally rad on a gravel rig.

The vast majority of gravel rides and riders never need anything over a 45. If you are actually riding stuff regularly that requires a tire over a 45 you might as well be on an XC MTB at that point if you are honest about it. 🙂

Yes, because non professional racers actually need power meters or the slew of other devices the gullible have been convinced they need to ride a bike recreationally. LOL

lol. “if you think just a few seconds” – oval chainrings for belt drives work in exactly the same way as they do for chain driven. there’s no difference. you can get them made up yourself, but it would be useful to have them made available by Gates or Pinion. PM pedals are less durable, often increase stack, cost the earth and unless axle based drastically reduce shoe clarance at pedal axle.

That’s nuts. An integral power meter in a Pinion? Oval rings with a Gates drive?

Of all these things, the power meter is the only one that might make a tiny bit of sense if you explained what your problem with pedal based meter is. If you don’t like the gearing, change a sprocket, so that’s a non-issue, and if you think just a few seconds of how an oval chainring would even work with a Pinion it should become clear that it doesn’t.