I think there is a bit of search secret sauce being revealed with how Google treats 301 as a canonical change. Search console tells you a redirected or missing page has an error because it does, even if it's a page you want forgotten. If you leave the page in place, update it's canonical, remove all internal links to it and drop it from the sitemap, and Google accepts the canonical change, the errors stop coming, your visitors can't find the page and search drops it properly, eventually.
So if you want silence and for Google errors to go away....
- change its canonical to point at the new URL
- drop all internal links pointing to the old page
- remove the old page from your sitemap
- Do not 301 or 404 the old version
- Add a notice to the old page saying the page has been updated and moved and link to the new url from the old page to entice anyone who finds it to go to the new version of the page.
- Reach out to webmasters who have linked to the old URL to update their site (John Mueller eludes to this in several videos from 2020)
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- Did he really say that the search team can't answer this question for the Google SEO team? Anyway, 301 is just a signal for canonicalization
Word of warning - if you leave a page in place to silence search console errors make sure the canonical tag points to the new url, otherwise you'll create a real mess and possibly a duplicate content problem which search console doesn't report as a problem.