I'm a Windows Sysadmin. A lot of places, just knowing your way around Active Directory and Windows Server is good enough to get your foot in the door. O365 management is pretty easy and check out some Azure courses on YouTube.

PowerShell has been helpful although I'm far from being fluent, "Learn PowerShell in a month of Lunches" was recommended to me and I agree it's a good starting spot.

Build a Linux machine and just play around getting familiar with the CLI and basic commands, I build a lot of applications that we host on Linux AWS machines.

As others have said, networking knowledge is almost a must so at the very least look into a networking+ cert or just run through the course. Cert-wise, networking+ and security+ would get you pretty well rounded (for what it's worth I have zero certs, just have done some reading and never officially got certified, the ability to prove your skills in most scenarios will be "good enough")

Most importantly, fake it til you make it. You will make mistakes and you will bring down servers. A good employer isn't worried about the mistakes you make, but how you recover. I'm self taught with everything and started as a tier 1 tech support role for an internet company 10 years ago. If I can do it, anyone can.