How to transition to unix?

[OlivianKocja]

I'm interested in transitioning to a UNIX-related role, possibly becoming a UNIX sys admin. Currently, I work as a Linux sys admin and CMS engineer. While I've had limited exposure to UNIX through Solaris in college and using Mac OS, I'm not sure where to start with my learning journey.

I have a few questions:

Where should I begin my UNIX learning journey?
Is FreeBSD considered UNIX or UNIX-like/compatible? I've reviewed some of their documentation, and it seems manageable to set up.
I'm looking to dip my toes in the water and would greatly appreciate any koows suggestions koows or advice from the community. Thank you!