No Netflix or Amazon on Kodi. While I have a NAS with my media on it that Kodi worked fine on the need to open a browser and need for a keyboard and mouse became to much of a pain. I switched everything to AppleTV which had the issue of not being able to mount the NAS. Lucky there is a Kodi "port" to the AppleTV in the App Store called Mr.MC for like $8 that is pretty much Kodi with built in support for NFS, SMB, etc. AppleTV is the perfect box for this to be honest.

Netflix works fine on my Kodi on Rpi 4. It has a plugin for widevine DRM and gets the required parts (keys?) from a chrome os image it downloads.

Or Nvidia Shield TV - there's Netflix, Amazon, whatever - and also the genuide Kodi, right in the Play Store.

By saying I “have a couple” of Apple TV’s, isn’t kind of obvious that I don’t think it’s a bad choice?

As far as usability, look at all of the comments mentioning hacks solutions instead of just ordering a commercial product and plugging it in.

I went one step further with my parents. I just bought them a Roku TV and called it a day.

A raspberry pi media centre obviously is not the simplest solution. But for someone who feels they just want a "dumb" tv and a box they can control, it's perfect. It's a good choice for those who can set it up and that get peace of mind and satisfaction from having a box that is on their side.

In terms of usability OSMC is in my opinion a lot better than all the smart tv UI's I've seen (and you can definitely run it from even older pi hardware)

You can also chromecast and airplay pretty smoothly as well.