My site got indexed by Google in 3 days — and landed on page 1

After my server got hit by cryptomining malware, I spent 2 weeks rebuilding and migrating products instead of thinking about SEO.
Finally submitted the sitemap on April 14. Google indexed it on April 17 — just 3 days. Homepage came in at position 10.2, right at the bottom of page 1.
I'm a self-taught solo developer building a micro-SaaS portfolio at saaslic.com. No CS background, no SEO knowledge — just learning as I go.
Two questions for the community:

How do you push a new site from the bottom of page 1 into the top 5?
Running multiple products under one domain — does that help or hurt SEO?

Any advice welcome!