Good to hear, I haven´t tried myself a portrait app dev yet, but when I first switched to GLB14 it happened naturally so I changed it to be landscape.
Let me try to explain:
V12 was kind of always portrait by core, I recall the drop down menu always came from the left side and it sucked (when holding it landscape to play).
V14 got that orientation correct, but the system I was using made my app portrait instead of the original intend (landscape), so I corrected it.
I don´t remember the exact settings be it a setscreen or project options (9998x9999) or just stating a lower resolution first, but it is nice that it worked out for you.
