What challenges exactly?
It's never been all that difficult if you have a consolidated library.
If not, then issues canaries since you need to recreate the path to the media files exactly on the external drive and that can be difficult to do.
If you have a consolidated library, then you can just point iTunes to the iTunes Library.itl file on the external drive by holding down the shift key when starting iTunes and it should just load it from there without much issue.
Issues may arise if your library is not consolidated as then iTunes may not know where to find the music files if the library file is on an external drive.
click here ➜ Make a split library portable - Apple Community
and here ➜ Move your iTunes library to another computer - Apple Support
Stop at step 2 under "Restoring from a backup" and instead just point iTunes to the library file on the external drive.