Sitemap audit
Every sitemap's status, the ones robots.txt lists but nobody submitted, a live check of a sample with an estimated indexed share, and previewed fixes.
Audit my sitemaps in Search Console and fix what's broken. List my Search Console properties first and ask which one to audit if I have more than one. (1) List every submitted sitemap with its status: last submitted and last downloaded, pending, errors and warnings, URLs submitted. Also list the sitemaps my robots.txt declares and say which were never submitted. (2) Run the sitemap audit on each sitemap that matters. Ask me how many URLs to sample for the live check and how many of those to inspect for an indexed share, and suggest numbers that fit the sitemap's size (each inspection uses one of the property's 2,000 daily URL Inspection calls). Report the URL count, duplicates, URLs outside the property, invalid or future lastmod dates, and every sampled URL that redirects, returns an error, carries a noindex or has a canonical pointing elsewhere, since none of those belong in a sitemap. (3) Give the estimated share of sitemap URLs Google has indexed, with examples of the ones it hasn't, and say it's an estimate from a sample. (4) Recommend the changes: sitemaps to submit (robots.txt ones nobody submitted), to resubmit after a fix, or to remove because they're dead or duplicated. Preview each change with submit_sitemap or delete_sitemap and wait for my confirmation before executing. Removing a sitemap only stops Search Console tracking it; URLs already indexed stay indexed.
Why this works
Search Console's API no longer says how many of a sitemap's URLs are indexed, and its Page indexing report has no API at all. The audit reads the sitemap the way Google does and inspects a sample, so you get an estimate back, plus any sitemap robots.txt lists that nobody submitted.