Totally understandable!
Window sizing is definitely complicated in Godot - 1 single aspect missing and it goes pear-shaped. One of my half baked projects included dynamic menus that changed according to screen rotation along with ensuring the resolution didn't break it - i think the many days of frustration fiddling with that helped me a little, but oh my gosh it was one long massive headache (i got what i was after but it killed my motivation for that project). xD