@Azurezaber
At the moment this isn't possible but you could put those messengers in a webpanel so you don't have to leave your active tab.
To add a webpanel press "F4" --> click on the "+" on the left side --> enter url of your webbased messenger --> press ok
In Settings --> Keyboard --> section "View" you can ad shortcuts to fast access the correct panel if you like.
In case your messenger is shown incorrectly go to the webpanel and rightclick on the bar where the reload and homebutton of said panel are and select "use dektop version" or "use mobile version" as you like.
Of course this is just a workaround to your idea - so please feel free to post your feature suggestion in this thread so others can upvote your idea as you can do with the suggestion of other users to show importance for needs and wishes of the users to the vivaldi developers.