Drivetrain

Groupsets
Cranksets
Cassette
Derailleurs
Shifters [& brake levels]

Bottom bracket

MULLET: https://bikepacking.com/gear/guide-to-mullet-drivetrains/

https://www.cyclingabout.com/low-climbing-gears-road-bike-crankset/

https://www.cyclingabout.com/low-gear-ratios-from-modern-2x-drivetrains/

https://www.cyclingabout.com/low-climbing-gears-road-bike-crankset/#white-industries-vbc-cranksets-40-24t

Bike Sauce: How big are the jumps on 1x vs 2x: https://www.youtube.com/watch?v=9BBN6NrDBx8

calculating derailleur total capacity

https://bicycles.stackexchange.com/questions/7264/how-to-calculate-the-capacity-of-a-rear-derailleur#:~:text=Determine%20Maximum%20Cassette%20Cog%20Difference,the%20Maximum%20Cassette%20Cog%20Difference

BEST OPTIONS

SHIMANO

Shimano GRX 12 Speed 1x ("Unstoppable"): 40 or 42 chainring; 10-51 cassette; 40T chainring: Gear inches (650B x 50mm): 40T X 10-51 = 21-108; Gear inches (650B x 50mm): 42T X 10-51 = 22-113

Shimano GRX 10 speed 2x (RX400): (650b X 50mm) (46/30 X 11-36): 22-113 gear inches

SRAM

Apex eagle mechanical (40 or 42T): Gear inches (650B X 50mm): 40 X 10-52 = 21 to 108 gear inches; Gear inches (650B X 50mm): 42 X 10-52 = 21 to 113 gear inches

Mullet 1x (electronic): Eagle cassette (10-52) and derailleur + Road crank (40t) and eTap AXS shifters (electronic): 40 x 10-52 = 20.4-106 gear inches

2x (electronic): Force XPLR eTap AXS 2x: 43/30 X 10-36 = 22-114 gear inches

MICROSHIFT

Microshift Sword

10 speed: 2x: 29/46 x 11-38; gear inches: 22-113

S Ride