I know there are cranks available but long cage rear derailleurs and shifters for a triple are gone. Shimano makes Tiagra, SRAM and Campagnolo have abandoned it. Plus Shimano front derailleurs seem to work best with a 53T big ring. Their MTB fronts are not compatible with road shifters. I am not interested in barcons for this build. Sadly I seem to be SOL.
Shimano Sora 3x9 STI
Shimano Alivio FCT4060 crankset 48x36x26t
Shimano Sora R3030 front derailleur
Shimano Alivio M4000 rear derailleur
Shimano Alivio or another 9 speed cassette with gearing you want
various 9 speed chain
A Sora triple FD works perfectly fine with an MTB crank with trekking gearing like the one listed.
Im pretty sure the spec above is standard on Surly DT and Trek 520.