1x12 Drivetrain
With a large cassette up to 51t, a 1x12 drivetrain climbs any hill and has enough speed to go as fast as you want.
Gravel bikes paved the way for 1x systems, desiring simpler drivetrains and not caring as much about steps in cadence. The additional gears makes that less of an issue anyway.
New freehub types
New hub types from Shimano (microspline) and Sram (XD) allow for a 10t top gear. This lets you have a smaller max chainring in front, which fits closer to the frame.