The default jellyfin client works great also on my NVIDIA shield.

Young children and non technical adults can use it as easily as any streaming app. I guess you can tweak and theme it endlessly to look like your favourite streaming app but I haven’t felt the need to so far.

Self-hosting always involves a bit of jankiness, if you can’t handle that then back to overpriced subscriptions and spyware you go.

SenPlayer is also very good on ATV.