HN user
Microsoft's latest lie is primed to created the largest single E-waste event in human history, argues Timothy Allen, Principal Engineer at the Wharton School, in an article for Technical.ly. The article gives practical suggestions, and argues the migration from Windows 10 to Linux Mint is easier than Windows 10 to Windows 11.
I don't believe it is "open" - although you have the code to modify, the license will make it very clear that it is anything but "open."
I've used WordPress for years. It's great for a simple blog, but not any kind of complex CMS, IMHO. After adding a few plugins, maintaining it is a nightmare; and I won't get into the database design underneath.
Another vote for Wagtail: my team has moved to it and have found it to be wonderful. It is the first time our tech, content, UX and marketing teams all agree on a CMS being wonderful. Streamfield is an absolutely killer feature. Our writers love the editor interface, which was clearly designed by and for content creators, and not by a bored developer like me.
Check out Wagtail. It takes a little bit more planning to get started, but wow, does it pay off in the long run.
It is truly free and open-source, released under the BSD license.