If you're planning on using a Shimano MTB rear mech with 10 speed road shifters, you'll need to use a 9 speed rear mech. It'll work fine if you do.
This.
Or even Microshift derailleur.
@Brommers started
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If you're planning on using a Shimano MTB rear mech with 10 speed road shifters, you'll need to use a 9 speed rear mech. It'll work fine if you do.