You should have given all the employees equity when they joined. It's better to give them equity sooner rather than later, but definitely before the next funding round (because the strike price has to be higher).

Employees with drone experience are in high demand right now. You have to give them equity to compete with other startups, as well as Amazon, Google, DJI, and others that can pay higher salaries.

Investors often have good advice from years of experience, but ultimately the CEO has to make the decisions.