Calibre for local book directory. Since I also self hosting, I have a Kavita and calibre-web for other stuff like mangas.

You don’t need the original anymore. Majority of the original are just encrypted (DRMed) .awz, .pdf or whatever the publisher gave to Amazon. After you’ve done dedrm you should have the same content as original files. Storing all those working files just fill up your disks. Now there’s a potential loss in quality if Amazon or other online distributor do some type of optimization to the original files they received, which they do for a lot of manga, but there’s nothing you can do about that one besides not buying it from that reseller again.