Mobile ad blocking is a little more challenging to set up than desktop, but here are some basics of my device setup to get started. This is compatible with both iOS and unrooted Android. After over a decade of running rooted Android starting with my first Android phone, I'm finally running unrooted for the first time ever and it forced me to read about some different ways of blocking ads from what I'm used to doing.
Private DNS: NextDNS
https://nextdns.io/
300K queries per month are included in their free plan, which is well above my typical mobile usage. Their web control panel gives you a lot of configuration options. Their paid plans are affordable too. Setting up ad and malware blocking at the DNS level is the easiest way to filter out junk without having to make changes to your actual device at the operating system/file system level, which is good considering both Apple and Google are essentially anti-ownership now.
Browser: Firefox mobile or any forks that have extension support with uBlock Origin
Extension support is essential to making this work. This is also the custom filter I use to prevent that AI Overview garbage from appearing in Google searches. On mobile though, lately I've started using DuckDuckGo as my default search engine.
google.com##h1:has-text(/^AI Overview$/):upward(7)
google.com##.hdzaWe
Another alternative that I haven't tested is Brave browser for mobile, but it also has a robust ad blocker that has functionality similar to uBlock Origin from what I understand. I have Brave as my teritary browser on my desktop PC and I never really explored what its built-in ad blocker is capable of, but I know it's more capable than what's found in other browsers and it can use blocklists that are compatible with uBO.
YouTube (Android): Revanced
https://revanced.app/
I've been using this for years back when it was called YouTube Vanced. It needs to be updated perhaps once a year or so as Google deprecates old versions of the YouTube app preventing video playback, so periodically, I patch a newer version of the app with the Revanced patches and check that all my previous settings are still working. It has a slight learning curve, but it's worth it. I will never use regular YouTube on Android again.
YouTube (iOS)
There are a few options including browser-based as well as alternative apps. I can't say that I'm familiar with all of them or know which ones work the best, but here are some ideas:
Ad block test:
https://adblock.turtlecute.org/
Use this test after you have everything configured. Firefox/uBO has documented incompatibilities with this site, but this is my result in Whale, which is a Chromium-based browser with some basic internal ad block filtering, plus DNS-level filtering with NextDNS.
One thing that I no longer use that I did in the past is VPN tunnel ad block software. Apps that do this include Blokada and AdGuard. I've found them to be problematic because they can sometimes cause conflicts elsewhere, like connecting to in-flight Wi-Fi or other networks that require authentication. Also, since the filtering is performed at the device level, those apps may incur a slight performance hit on the device compared to DNS-based filtering.
So to be perfectly honest, I have no idea what it's like to have my phone serve me an ad about something I was discussing out loud with present company. I
never see ads in my mobile browser, YouTube, or free apps that are supported by ads served by CDNs that are on common public blocklists.