> I think any empty Qt/GTK app eats 40 MB at least.
Classic GTK is (much) better (RSS on Linux):
GTK2 14 MB
GTK3 24 MB
Once it was decided that a desktop application must have fancy animation effects (like on smartphones) and be rendered completely on GPU things got very different: GTK4 98 MB
GTK used to be considered the bloated option along with QT. My first Linux box had 128MB of ram and it was screaming fast.