Can you add the Jellyfin app to your TV? https://www.amazon.com/Jellyfin-for-Fire-TV/dp/B07TX7Z725
From there you should be able to enter your server info and login credentials.
NOTE: there are official Jellyfin clients on the official app stores for Android and Amazon devices - I personally prefer Kodi, but itโs worth trying them both yourself to see what works best for you:
What about this link? ๐ to Jellyfin on Amazon
The 4k version should be capable of handling what you want.
I use the standard HD version, so cannot give evidence on higher demands.
No, that is a different app. If you have an Amazon Fire TV stick, please use Jellyfin for Fire TV.