How to connect with founders of early stage startups?

I was curious if there is a way to find about promising founders who are working on a new project/startup that does not have any significant online footprint yet.

In this context, for me it is not a "very" early stage startup if I can read about it on AngelList or they have more than just a landing page.

There can be many signals for promising founders like their previous jobs or ventures or experience in that domain.

I believe it is easier for people who already know these founders as friends or colleagues but for others, not so much.

For example - Linear App in 2019 or Vercel in 2015 and such.