How to find a fitting drivetrain
135mm quick release hubs are still common. 26” 135mm 10 speed cassette compatible wheels should be easy to obtain.

Make sure to get a Hollowtech BB that is specific to MTBs. These fit 73mm shells and 68mm shells with included spacers, and are compatible with MTB cranks. Road Hollowtech BBs only fit 68mm shells. 

For the rear derailleur, "23-28t Close ratio" and "32-36t Wide ratio” refers to the size of the largest cassette sprocket supported. If you want low gears you want the wide ratio option and a 11-32, 11-34 or 11-36 cassette. Do some research or gear ratios to decide what range you need.