I bought a Raspberry Pi specifically for this, then I realized the obvious, it's useless outside of the house :) It was good for the old Wi-Fi-only iPad the little one was using, but pointless for my needs. I like having the Pi to play with though.
Setup a VPN tunnel for your DNS traffic and benefit from your Pi-hole wherever you go. I use Tasker on Android to automatically detect when I'm not on home wifi and then trigger OpenVPN to connect to my home VPN for Pihole and local network access.
On my phone I use Firefox and uBlock Origin and I don't install ad funded apps, or any closed source apps I'm not forced to have, so I haven't really felt the need to go that route. The only ad supported app my kids use on their devices is YouTube but, last I checked, Pi-Hole isn't able to block those ads.