I imagine something like Ontrack will quote you at least $1000
If you consider the data worth that then I would go for one of the big known firms.
If not then I would start researching how to replace a pcb and risk losing the data.

I would go for a reverse proxy to get ssl running.
https://jellyfin.org/docs/general/networking/#running-jellyfin-behind-a-reverse-proxy

Handling users with forgotten passwords is, sadly, a manual chore for the administrator.
https://jellyfin.org/docs/general/server/users/adding-managing-users#profile

I didn’t enjoy using Jellyfin for audiobooks, on my android I use the Jellyfin client to download the book I wanna listen to and then I use AudioAnchor for listening to it.

I haven’t used Plex myself but Jellyfin doesn’t create any kind of meta files in the library folders. If that is true for Plex as well then I don’t see why it would be a problem to point them at the same shared library.

As a result I imagine more users will look at other offerings such as Jellyfin.
https://github.com/jellyfin/jellyfin
https://jellyfin.org/

Open them up with a screwdriver and then either smash the disks inside or continue dissassembling it for fun before destroying the disks.