You can still download firefox on iOS. Snowhaze for really sensitive stuff. Safari for anything else. Using different browsers for different purposes help defend against profiling.
I personally use firefox for work stuff, firefox focus for banking, safari for personal and snowhaze for ehem.. err adult stuff.
I think the history and bookmarks are separate. Only the engine is the same. For safari, enabling adguard and other extensions does wonders for privacy. :)
I agree they’re overkill. But there are sites that detect the adblocker and I just experiment which one they don’t detect. Most of the time, adguard does amazing. But some websites only adblock is not detected. So it’s a cat and mouse game for me. :) I installed them all just in case and activate and deactivate depending on which sites I am on.