I’m going to agree with a lot of the other posters and say QT with QT creator. It’s a tested and well though out implementation. It’s signals and slots event system is straight forward and easy to learn.
Whatever route you take learn Model View Controller (MVC). It gets in the mindset of keeping your data model seprate from things that use the data and things that change the data.
Linux isn’t going to help much when the applications are using a lot ram. Firefox is an absolute ram hog linux or windows. Linux is just going to use less of the ram for it self.