The old favicon is the tell everyone's walking past. Google isn't slow-crawling your site, it's still serving the OLD entity from cache -> it hasn't even refreshed the one page it kept indexed. That's not a technical fault on your end, that's a reborn-domain quarantine: the domain died, changed hands (maybe), came back as a different site, and Google reset its crawl priority to near zero until it re-earns trust.
Three things I'd actually do, in order:
- Check the Wayback snapshots for the year you didn't own it. "Someone snapped it up, or so I believe, I'm not 100% sure" is the loudest sentence in your post. If the interim owner parked it or ran junk on it, that's your reset explained. Still fixable, just slowly.
- Forget the Indexing API for this. Google's own docs restrict it to pages with job posting or livestream structured data. The "success" response means the request was accepted, not that a crawl was scheduled. For a normal SaaS site it does nothing.
- Make the crawl paths physical: a Sitemap: line in robots.txt (the GSC submission clearly isn't being read), hard internal links from the one indexed homepage to your money pages, and a few real external links pointing at INNER pages, not the homepage. Inner-page links are what force discovery when the front door is cached.
Timeline honesty: two weeks is nothing for this situation. I've watched reborn domains sit in the penalty box for 30-90 days with everything technically perfect. Watch your server logs for Googlebot on inner URLs, that's the only signal that matters right now. The day it starts fetching /prices is the day the clock starts.