You can usually run Linux from something like a bootable USB stick to try it out.
Windows is "open" in the sense that there are all sorts of hacks and apps(often free) that allow you to change the behaviour and appearance.
Restore old Right-click Context menu in Windows 11
You can even use the free version of MS Visual Studio to develop your own apps.
Unless you're planning on modifying the Linux OS and rebuilding it yourself, being "open source" is meaningless.