I doubt all the Chromium clones would evenly support "normal" iOS integrations, and the ability to (privately) deal with, for example, universal links, App Clips, or even that banner offering a website visitor to use the native app.
I understand the sentiment for wanting to use custom features on desktop, but a phone needs to be much more reliable than this - you can't have something working "sometimes" or for users to have to retry or change settings on the go. Imagine a stressful situation at the airport, and the app you are using needs you to switch browsers or download another app to work...
This is something that works just fine for me over on Android, in Firefox mobile. Actually, i assume that the mobile browsers would offer all of these capabilities, assuming apple allows access to, and documents their apis appropriately.
Why is it that we somehow defend apple having proprietary/exclusive Apis that nobody else has as good? It's essentially the same game as it was with internet explorer.
I think if apple just opened up their eco system the other browsers would support these features before long, or app developers would include them in their apps instead of relying on browsers.
It's not like apple is the only one with capable engineers, they just stop everyone else from using their stuff to the fullest
This would still be true in the case where external web browsers were allowed - you can still rely on Webkit being available on all phones, but if you need access to APIs not provided by apple you can revert to bundling a different browser engine