The chief technology officer owns technology strategy. Depending on the organisation the role centres on the product being built, on internal technology, or both; where there is also a CIO, the CTO usually faces the product and the CIO faces internal systems.
In workplace decisions the CTO or CIO is the gatekeeper for anything joining the stack: does it support SSO and SCIM, does it have a real API, where does the data live, and will it create shadow-IT problems or solve them. Workplace platforms that answer those questions in the first meeting tend to make the shortlist.