Frankly, if they aren’t tech savvy, you should just have them use Authy. No, it’s not open source, but it’s just fine for the average user.
Definitely the Kobo Libra 2 or the Kobo Nia. I bought both a Kindle and a Kobo Libra 2 and ended up returning the Kindle because book piracy was a pain. The overall Kobo user experience is just a whole lot more pleasant.
If you really want to build an awesome Plex/Jellyfin library, start using Usenet instead of torrents.
Or LunaSea on iOS
Frankly, if they aren’t tech savvy, you should just have them use Authy. No, it’s not open source, but it’s just fine for the average user.