Technical community launched a couple of years ago at Ignite, almost feels like an update to the old TechNet forums.

https://techcommunity.microsoft.com/

Great place for all things Microsoft and staying up to date

https://www.reddit.com/r/microsoft/

And always reading and updating from MS official source.

https://docs.microsoft.com/en-us/microsoft-365/

https://lwn.net/

https://www.linuxquestions.org/linux/answers