All you need is a VPN (such as OpenVPN) or SNT (such as ZeroTier) to your home router with your Pi-Hole. Which is conceivable on mobile, though it does cost some power (but you also don't see/load the ads saving bandwidth and CPU cycles). A Pi-Hole on a Raspberry Pi doesn't cost much electricity-wise; it does cost something for the hardware but you can use the RPi for more that just Pi-Hole. An alternative is Ublock Origin which works in Firefox and Chrome (even Firefox Mobile) but it isn't OS-wide.