I installed EndeavourOS on a 2013 MacBook Air a month ago for a backpack trip. It was light enough to carry around and it was cheap enough I did not worry about it being broken or stolen.
It works fantastically. LibreOffice, Outlook online, Teams, OBS Studio, Distrobox, Docker, IntellijIDEA. I have even played a little Steam on it. The only thing that was not out of the box was the iSight camera and even that was a one line command after install.
The only software that let me down was DaVinci Resolve. The integrated GPU is not supported.
All I did was hold down Option at boot so I could boot off the USB and then I let the installer do the work. Anybody could do it.
They are probably saying the shared POSIX underpinnings means greater commonality between macOS and Linux and therefore easier porting. That is likely true to some extent but real apps are written to Apple proprietary APIs and therefore that advantage is largely nullified.
In terms of effort to bring apps over, there has been far, far more effort put into porting Windows apps and so that task ( at this point ) is generally easier. It may have been less effort to port macOS at the start ( eg. GNUstep ) but that work has still largely never been done.
It is easy to move POSIX world apps to macOS. It is not as easy to go the other way.