Are we talking iOS or WinO/S issue? In either case if you wiped clean and reinstalled OEM or Custom anything that was on there before is gone. And there is no way to get them back and if there is no sync to something else that also means there's no sync restore to happen. So if Erased means wiped clean then nothing more can be done.

This is an IOS issue. I backed up the computer to an external hard drive, but seem to be unable to find any firefox items in my backup. These bookmarks are extremely important to me since they are my only links to one year of research and supporting saved web files.

IOS is the mobile OS for iPhones and older iPads (newer ones use iPadOS) https://en.wikipedia.org/wiki/IOS

What you have is macOS https://en.wikipedia.org/wiki/MacOS

Your settings like Bookmarks, Passwords and such are not in the Firefox folder but in a separate place as hopefully the backup method saved your Profile(s) that was located in Application Support folder > Firefox folder > Profiles folder

https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data#w_finding-your-profile-without-opening-firefox

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile