It's more easier with Opera than you think. Just tap the 3 dots menu and then tap the icon with the 3 dots connected to each other. Then you can select the app you want to send your url with.
In order to do this, one has to open each link he wants to "share", and it's very inconvenient to share more than one link. For example, I use Pocket to save links to read later, and in Opera I would have to wait while each page opens, and then I'd have to close it or go back, while in other browsers I can just long press on each link -> "Share" -> "Save to Pocket".