If the sizing is not going to be a problem, Travel Agents are what you want to convert a road brake lever to the correct pull for a v-brake. on the other hand, you could also get some "mini v-brakes" which have shorter arms and a different pull ratio that will play nice with road brake levers.

You didn't say what drivetrain components your bike currently has. I can't remember, so I'll just ask the question for you: is the pull ratio for Shimano (and Microshift) the same for 8-speed road and mountain drivetrains? I know Shimano higher-end drivetrains are different (so you cannot reliably use a Ultegra 11-speed shifter for accurate shifting with a XTR 11-speed derailer), but 8-speed stuff might play nice.

I agree this sounds like a lot of money and effort to dump into a flat-bar hybrid to make a compromised pseudo-road frankenbike when you could make a killing selling this bike (because of the high demand for bikes due to COVID) and buy something MUCH better and probably spend marginally more money in the end.