Pin the new Opera Mail standalone client in the task bar. Turn on your PC and click both Opera and Opera Mail icons. There you go, less than 3 seconds (a click) and you have your e-mail.
Keyboard shortcuts: Windows + position in the task bar, custom keyboard shortcut Windows allow you to set to the shortcut in its proprieties or AutoHotkey.
Please note I’m only showing the fact the rewrite of M2 into the new Opera would be a waste of resources. I’m not “against” people that like the integrated e-mail client but the great majority can’t justify why it’s better integrated (not to say they can’t justify the need to use a client over web-mail to start).