Publishing VBCS changes so they are visible in some non-prod environments but not others

Summary:

How can we make changes and see them in one non-prod environment, but keep them separate to changes we want to make and see in other non-prod environments?

Content (please ensure you mask any confidential information):

Our path-to-prod is DEV1 → DEV3 → TEST and then PROD. We use DEV2, DEV4, DEV15, and DEV17 as playpens for separate areas/teams.

I've spent weeks trawling through all of the Oracle documentation, blogs, webinars, community chats about VBCS and branching strategies, best practices etc.

We have one project for our organisation, as per Oracle best practice, with one HCM extension and one Procurement extension.