Extensions only work with Safari on iOS/iPadOS. To use a content blocker with Firefox, it’s better to use Firefox Focus. DDG browser is fine too.
I do still say use Safari with a content blocker like Wipr/Adgurad/Ublock lite etc.
For now ublock lite doesn't have the feature parity with Adguard.
Wipr 2's developer is planning to use Apple's introduction of URL filtering with their OS 26 releases, which will extend Wipr’s blocking to all apps on our device. It acts at the network level, but it can access none of our data.
https://kaylees.site/wipr-filtr.html
Pretty sure other content blocker developers will jump on it too.
Not OP, but using a similar setup: iCloud for government, banks, and a custom domain with Proton Mail for everything else. A few major banks here in my country have hardcoded domain names to include only Gmail, Outlook, Yahoo, iCloud, and a few local providers. The same is true for the Income Tax portal. Out of the given options, iCloud is relatively more private.
I've encountered a few other websites doing this kind of lazy implementation. Hide My Email by Apple works in such cases too, where I don't want to disclose my primary iCloud address, which is accepted globally especially since it ends with @icloud.com.
Personally, I use it through Safari with Wipr 2. Wipr's developer is pretty active and responsive too. Another option is using Adguard Pro. Vinegar is a good option too, but it's developer suggests us to use a different adblocker and use Vinegar for it's main purpose of forcing the native HTML 5 player.
If you're okay with Brave's crypto shenanigans, it works well with YouTube too.
I use YouTube almost always signed out. Along with icloud private relay enabled, it does minimise the amount of data that Google can collect. I would prefer to use Invidious or Piped, but they bug out quite often with YouTube playing a cat and mouse game.
Extensions only work with Safari on iOS/iPadOS. To use a content blocker with Firefox, it’s better to use Firefox Focus. DDG browser is fine too. I do still say use Safari with a content blocker like Wipr/Adgurad/Ublock lite etc.