Service account or OAuth for Search Console
The choice is not OAuth against service accounts. Both are OAuth 2.0. The question is whose Google account holds permission on the property, and whether a person has to be there.
Shipping notes, in public
How we build the thing that publishes your changelog, your blog and your release notes.
What sticks when you submit a sitemap URL to Search Console
The submission itself can be undone. The saved address is the part that keeps acting on its own, because it is re-submitted every time you publish.
Search Console API returns 403: four causes, one fix each
Google's 403 carries a reason code that names which of four failures happened. Read the reason before you change anything, because the fix is different in each case.