Is it possible to make some selected via's exposed in KiCad? Although the option "Do not tent vias" is helpful but it is a global setting. Is there any option so that some vias will be left unmasked?
The best way to achieve this would be to create a new via footprint that has no soldermask layer. Then, add this footprint to your board (and be sure to lock it, so it doesn't get removed on a netlist update) and connect the traces to it.