Not the guy you asked, but I use Projectivy Launcher. It's not FOSS, but it does a decent job of putting a suggestions/up next feed on the homescreen and is fairly customizable.
Yeah, this doesn't seem to provide anything a better launcher + Pi-hole don't already provide. At least on mobile, the ad blockers help when I'm away from home and not going through the Pi-hole for DNS queries...but my tv doesn't leave the house much.
An option for you. Setup a WireGuard server on your network and use the WireGuard mobile app to use that VPN connection when not connected to your home WiFi. Then you’re always using the internet through your pihole. That’s how I have mine setup and it works well.
I use Tailscale when the need arises, but I honestly don't see ads on my phone very often even without the Pi-hole between good browsers, revanced, and not playing shitty mobile games.
I was mostly just questioning the usefulness of AdGuard on a tv box. It seems to have a pretty narrow scope, which could be better addressed through other means (better in that DNS-based blocking helps the entire network, not just the tv).