I used a 31.8 band on front mech mount like this;
And modded an old 10speed SLX shifter (cut part of the original mount off with a hacksaw, leaving the threaded section on the shifter).
Cost was about 4quid from eBay…
Canecreek levers from crc were about £25 and work well with the Trp discs I have.
Using 1×10 – 40t on the front and 11-42 on the back gives offroad ability but spins out at about 25mph on the road (I usually tuck at this point anyway).
I had been using a Dia-comp thumb shifter, but it needed the full sweep of the shifter rotate to work with the mtb mech, as a result it interrupted hand position on the bars when in the mid portion of the block.