If you’re open to things similar to Plex, I’d recommend Jellyfin! Plex has been making some decisions lately that aren’t necessarily selfhoster friendly. A selfhosted instance of Plex still authenticates using Plex’s central servers (if you’re internet is out or Plex is down and you want to stream your own movies or shows, that won’t work due to failed authentication). That’s compared to your Jellyfin instance handling authentication locally. If you can contact your server, you can watch your media. Plex has also announced a credit skipping feature, uploading credit timing to their central servers that can be restored on complete rebuild. While they say it’s anonymous, they need some way to associate you and the proper credit timings, to send that back to you.
Jellyfin is earlier days in development, and you should check to see what clients are available to see if that would work with your hardware. But Jellyfin is definitely catching up, I’ve been very happy with their server and applications.
I doubt Reddit builds a decent search engine, that doesn’t actually help them at all.
If users can search, they find a previous post pertaining to what they want to see/know and they move on.
If there’s no search, users can’t find old posts or comments so they make new posts about a previously posted topic and more comments are made as other users react. That’s more content, even if low quality from a user perspective, that shows engagement which can be sold to advertisers.
That’s before considering the engineering effort it takes to make a good search engine, constantly fine tune that algorithm, and try to outpace those that are trying to game the search algorithm.