Genuinely curious -- why would OP give away shares to someone else? Those shares were vested in the past as a reward for their contributions so far, and commensurate with the risk OP took in a venture that could pivot into something else. So shouldn't they keep those shares as a reward but cease further vesting? I thought this was the whole point of why founders vest their own ownership. If they want to bring on a CTO they will have to dilute everyone, but this is the consequence of pivoting into a new space that no longer has founder-market fit (i.e. the original idea was risky as it led to a pivot away from a founder's competency, therefore everyone should dilute equally as a consequence).