Mobilism is a source for pirated ios apps, but it’s quite limited. I agree with the people mentioning pihole, but if you have to block ads on-device change the dns settings and/or use brave browser, which has the most adblock capabilities on iOS. Altstore is an alternative appstore (AltStore PAL in europe costs 1,50 a year in europe iirc) which has alot of cool apps and allows sideloading of ipa files on-device. I generally do recommend a pixel with grapheneOS, though I haven’t tried it myself yet.
Edit: Forgot to mention some of the downsides of AltStore, which includes needing to refresh the app once a week wirelessly or wired via a computer running Altserver