A PC will work fine for general viewing but might be a problem for those looking for more advanced features, e.g. Dolby Vision.

Apple TV has a few things one may consider “ads”, but they’re limited to promotion of Apple’s own shows (no third parties) and can be done away with by simply ignoring the stock TV app and moving it off the top row of the home screen where it’ll never get highlighted. They haven’t bothered me personally, and my Apple TV 4K working flawlessly since buying it in 2017 is worth that tiny tradeoff.

I've been looking into Apple TV 4K boxes as an alternative to Roku --- I'm sick of their ads baked into the UI --- and I've read in a couple places online that if you put the Photos app in first position of the top bar you'll get a slideshow of whatever photos are in there instead of promos for a particular app's shows.

Is that so?

It'd definitely put me across the line into switching. With Jellyfin now supported with the native Swiftfin app it'd have everything I need.

Yeah, that’s correct. Only apps in the top row that are highlighted can display content on the home screen and the leftmost app is highlighted at boot/wake.

I don’t have any experience with Jellyfin+Swiftfin but Infuse has worked well with my Plex server.

As a sidenote, to test this I woke the the old 2015 Apple TV HD that the 4K model replaced and to my surprise it’d updated itself to the latest tvOS and still runs smoothly. Not bad for an 8 year old device, and no doubt in better shape than most competitors of a similar age.