9 speed shifter and 10 speed mech shouldn’t work (properly) in either Shimanoland or SRAMland.
As correctly pointed out above several times, the shifters pull a different amount of cable.
Neither side knows how many clicks there are at the other end. They just want the right amount of cable, pls.
Up as far as 9sp Shimano vs SRAM was all you really needed to watch.
In 10sp Shimano road and mtb pull ratios are now different from each other and both different to either 9sp or SRAM. SRAM 10sp road and mtb pull ratios are interchangeable but slightly different to 9sp (still referred to as 1:1 in marketing)
Obviously with some tuning any combination will kinda sorta work possibly with the odd skipped mid ratio as suggested above – how acceptable this is depends on the individual. It may be no nastier than knackered old cables.
There are/have been various pulley and spacer bodges but YMMV. Using correct combinations is easier and more reliable.