Will those features transfer to iOS though? Last time I checked truly custom browsers are not allowed there and extensions could be easily interpreted as running downloaded third party code, which is also a common excuse for Apple to throw apps off the store.
Definitely not perfectly yet, but initial support is there for Chrome and Firefox extensions, though I also wonder how this will work with the app store policies.
Don't get too excited. Many extensions do not work. It's as if Kagi needs to work on the code to make particular extensions work. I'm sure neither Firefox nor Chromium need to do that.