Believe it or not these are all real companies that hire a variety of skill levels and even hire designers, frontend devs, support people, sales, marketing and so on. :) I mean not necessarily all of those companies are hiring all of those positions at every level this minute.

But my point is that, you can almost always find some way into an interesting company such that you may be able to eventually pivot to (or at least periodically work with) a team you're interested in.

Both Docker and Jetbrains are working on software projects just like the rest of us. There is still boring shit work to do that no one else wants to do, so they need junior devs to shovel it off to. So yes, they have juniors, mid-levels, and everything up to staff and beyond. They are no different than any other company.

The difference is probably that it is harder to get those jobs because everyone wants to work for the flashy exciting companies. I was considered for a job at Docker a long time ago (when I was an early-midlevel) and the recruiter told me that over 1,200 people applied in 5 days. For entry-level/intern positions I assume it is similar or even worse.