I wanted to be able to get at Apple's content distribution network directly instead of guessing when stuff would be made available to me, and found it convenient to have a physical installer handy so I made this

I was cleaning out my downloads over the weekend and came across this app for downloading versions of MacOS installers. It doesn't make a bootable volume, but that shouldn't be too difficult (I say this as a Mac user; I don't know about Linux and Windows). I'm not affiliated with the project.

https://github.com/ninxsoft/Mist

I wish it would work from Windows as I have a bricked Apple laptop which I want to revive.