@whataboutwolves I agree it should be there. I'm not sure I learned this keyboard shortcut in Opera, my experience may be from Firefox.
Ctrl+Shift+PgUp/PgDown has started working in Chrome for Windows only recently (it used to work on Linux for some time, apparently), and I welcome its appearance there. There also seems to be the F6, F6 key shortcut to enter tab selection mode, but I can't find this in Opera either.
right now if you get a new window all the workspaces are empty
Yes. Each workspace gets its own set of tabs for each window. You can use this to your advantage if you want. For example, if you just give the workspaces numbers for names and generic icons., you can put what you want in them in each window. You just have to remember what number is for what in each window.