Earlier quoted context omitted.
Curation is key and there need to be better tools. I strongly limit my kid's screen time, and was pleasantly surprised by the PBS kids video app (and to some extent the games app). I felt very comfortable leaving her alone with that at the designated screen times, as most programs had at least some educational component... or at least had some generic but positive moral lessons. And (key!) she gets personal choice in…
Torrent the shows you want her to see and setup Jellyfin server. I run one on a Xeon SOC from 2016, but i would be surprised if a Raspberry Pi 4 couldn't handle the transcoding. Install Jellyfin app on a tablet, you just built a curated version of Netflix.
[EDIT] Incidentally, Jellyfin doesn't have an allow-list, either. You have to put kids' content in a separate library. They have block lists based on tags, but not a more-useful allow-list. It's been requested and I've thought about doing it—I've looked at the code, looks pretty easy—but, LOL, I have kids! Which I expect is why all the other kid-havers requesting the feature haven't gotten around to it, either.
[EDIT AGAIN] The reason the separate-library solution kinda sucks is it fragments your content, so if you're browsing based on library you have to think "wait, did I decide this was OK for the kids' library?" and it doesn't de-dupe so if you put content in both (say, with hard links to avoid wasting disk space) they'll show up twice on accounts that can access both libraries, plus it means shelling in to move files around to change what's available, plus it's a huge PITA if you want multiple kids' accounts with different content (tags are easy—older kids gets all the kid tags as allowed, younger kids get a smaller set of kid-tags allowed). I'd also personally really like to be able to not display all my kid-friendly content to them all the time (too much choice, same as adults experience on streaming services) and change it up periodically (this also lets me push better things on them that they might not pick from a list of 100 but might pick from a list of 10) which makes the separate-library especially painful, since it means file-management actions every single time I want to change up the kids' library, rather than just some quick tag-shuffling on the Web UI, which I can just do from my phone in a pinch.