Doesn’t GNOME at least have a setting to change alt-tab to window- instead of app-based?
Cmd+Tab switches between applications, and Cmd+~ switches between windows of the current application.
That said, I rarely use Cmd+Tab anymore, I just move the mouse to the top left corner and pick, now that screen could use some UX improvements (i.e. hotkeys for the apps, and maybe grouping, since when you have a lot of open apps, it is hard to find what you are looking for).