Shimano GRX component series is the first dedicated gravel group w/ 10 & 11 speed options - Bikerumor
Shimano Drivetrain: Cross-Generation, Same # of Speeds Compatibility - Weight Weenies
parts - Shimano MTB and Road Components Compatibility - Bicycles Stack Exchange
Shimano's Deore 10 and 11-speed groups will bring your old bike up to speed | Mountain Bike Reviews Forum
Nas Cycling - Hi, Here's the list of all compatible shifters & RD combo for dropbar wide range (40t to 52t) gearing setup. This is base on the compatibility chart and known
M660 shifter with M5120 derailleur : r/bikewrench
Any bike mechanics, help needed....Ultegra 6870 and R8000 compatibility - Equipment - TrainerRoad
Selecting the Ideal Freehub Body for Your Cassette: Ultimate Guide
drivetrain - Will it cause problems if I use components from different series? - Bicycles Stack Exchange
Nas Cycling - Hi, I made a compatibility chart for a 2x10 mullet drivetrain. If you're looking to repurpose your old Shimano 10 speed road shifters for gravel riding, this might help