Trajectory of a [Pg] DBA

Hi all.

I'd like to tap into the list's experience regarding the job of a DBA
in general and Pg DBA in particular.

I see that most of the DBA job posts ask for Sr or Ssr which is
understandable given that databases are among a company’s most
valuable assets, but it is also an obvious catch-22. So I'd like to
ask the list's part- and full-time DBAs, if it's not too personal, how
they landed their jobs.

Is it an easier and more common entry point to be a part-time DBA e.g.
perform DBA duties as part of being a U**X sysadmin?

Is it more common to start as a developer and change focus to DBA?

In particular how does one go about starting as a Pg DBA? Is the most
common case by migrating from another DBMS?

TIA,
Thalis K.