" DosDude " - that is illegal and Let the Apple Lawyers and Law Courts decided this issue.
The method of Dosdude circumvents the Apple Licence Of Use.
One can be very sure the Law Offices of Apple would have a very easy win if there has not already been several wins.
As for Hidden High Sierra Download from the Apple Store - yes it is hidden. That is totally normal.
Even Big Sur macOS 11 released in November 2020 is hidden on the Apple Store.
But if one actually followed the methods outlined by more than one Contributor - it would work.
I know, I just attempted from the same Links Provided and yes can Download the Full Version 11.3.6. Though, can do nothing with it as this Computer does Not qualify for a 2017 Release of macOS . It is Too New to use High Sierra.