accideath

I second (third) an Intel ARC card. For the tasks you’ve named it doesn’t even really matter which one, even the smallest one is a transcoding powerhouse, doing multiple 4K transcodes with HDR tone mapping with ease.
Additionally, Intel drivers are wayyy better on Linux (TrueNAS) than Nvidia’s. Don’t even need to install them. I would go with any one you can get for a decent price, so probably the small A310. It doesn’t even need extra power. Sips like 30W or so.
If you want an upgrade still, A750s are also reasonably priced on the used market. Don’t get the A380 over the A310 unless they’re the same price. They perform almost identical and the 380 draws more power. Does also have more vram though, if you need that for immich.

And stay clear from AMD cards. They’re the goat for linux gaming but their video encoders are notably inferior to the other two. Not what you want for Jellyfin.

But they also do not care about picture quality beyond brightness, if at all.

I mean, it’s good in that case, too, but it’s also good if you have a Jellyfin server and want a device that supports modern standards like DolbyVision and that isn’t completely overflowing with ads.

Can I get support for DolbyVision using kodi or similar?

On that note, does anybody know a good set top box with DolbyVision support that doesn’t require Amazon or Google services?
Because the only one that comes to my mind would be an AppleTV and I don’t want to believe that’s the least terrible option…

It’s mostly a thing of what’s available for your phone. For pixels 6 and newer (and I think some new motorolas as of recently) you can use graphene. If you are on fairphone or a bunch of other devices, you have support for e/OS. In general, graphene is a bit more secure than e/OS, so if you have the choice, it’s probably the way to go but if you don’t have a pixel and don’t want to buy one, e/OS is probably one of the better maintained degoogled android versions out there.
Here you can find a list with a feature comparison.

Oftentimes it’s not a choice. Microsoft office is a de facto standard in many professional contexts.
I personally avoid using Microsoft products whenever I can but that doesn’t mean everybody has that luxury.

And I cannot blame anyone buying a perpetual licence when the alternative is a subscription.

They don’t have a history of undoing perpetual licenses though. I mean, I know people who still use a licensed copy of office 2000