1. Board policy first
Purpose, limits, authorised people, and review dates are decided before any purchase. The policy is the control everything else answers to.

Implement
Policy, acquisition, security, and oversight, in that order.
Purpose, limits, authorised people, and review dates are decided before any purchase. The policy is the control everything else answers to.
Purchases happen under the policy, by named people, with records the board and auditors can follow.
No single person can move company bitcoin alone. Signing requires more than one authorised holder, arranged so the company keeps control.
Regular review of who can sign, what happens when an executive leaves, and how a lost device is replaced without losing access.