Jellyfin a) only has the content you feed it, so you already have some knowledge about it and b) you can expand it with plugins and make the design however you like it.

Shouldn’t it have an SD card slot?

I had additional issues due to technical problems with the motherboard. For most people it won’t be nearly as hard. […] If you follow the steps perfectly you shouldn’t have issues.

You just described the linux experience. In 99% of the time, Linux just works. For 1% of the things, you have to apply above methodology. How is that worse than keeping on using windows?