The ability to install an ad blocker natively on the default browser is the reason I switched, and cannot stand androids anymore (after 5 android phones previously).
You can do this on iOS as well, but not for App Store apps.
So if you rebuild every week or pay Apple a yearly fee for the privilege of blocking ads on your own phone.
Unfortunately your only option is to pay Apple, since you cannot develop VPN extensions on a free account.
It's surprising to me that an easy-to-use set of scripts to do this for you hasn't popped up (to my knowledge). When Apple initially offered the "zero cost but you have to rebuild every week" solution, I was sure there'd be an idiot-proof solution to make that seamless within a few days.
Cydia Impactor can do this on-device, IIRC. But you still need to launch the app.
On Android, you can set Firefox as the default browser and configure uBlock as an add-on.
Default browser doesn't effect in-app browser frames which are becoming more and more common - half of webpages will be in chrome anyway.
I believe you can swap out the system webview as well?
Firefox Focus shipped with GeckoView[1] only yesterday.