Enderal and ForgottenStories is one, FS is fixed integrated as an addon on Steam + various updates
(Before there was only Enderal, but is no longer distributed or supported, Enderal without FS no longer exists)
but in both cases
you need Skyrim, 32bit on Steam (classic or legendary version).
See more information also here.
For Enderal you don't need an installation of Skyrim, you must only own it on Steam. It is a completely separate installation.
So you don't have to overwrite any version of Skyrim and an existing installation will not be changed.
!
Not the SkyrimSE-64bit version or Skyrim VR or similar, this will not make it work !
Skyrim-32bit is still available, it is only not shown in the steam search anymore,
alternatively there are still several dealers on internet or in retail stores that carry it.