Also - not quite what you are asking for, but perhaps useful. Many apps have a Window > Bring All to Front menu option, which brings all the windows for that app to the front.
I’ve added a key shortcut for that, using System Preferences > Keyboard > Shortcuts > App Shortcuts > + > All Applications). I chose ctrl-alt-shift-cmd-F, which doesn’t seem to conflict with anything else on my system.
I use this fairly often, particularly with the Finder I think, eg when I’m wanting to drag from one window to another.
If you do this, note it’s worth mapping both “Bring All to Front” and “Bring All To Front” - note the difference in caps - sadly, apps aren’t consistent with this and the spelling needs to exactly match the menu title for this to work.