My suggestion is to make this feature like this:
in right upper menu there is still the share button, where it can be selected and changed the default share app.
Then Web pages can be shared quick and without additional steps by "long pressing Home button" in (home icon in lower navigation bar.
Example: you're on example.com page, then long press "Home" icon and the page is opening in default share app.
Thank you Opera team, have a nice christmas