I’m not savvy enough to be able to differentiate the tools in discussion here, but I’m aware of a Qt project (that initially started as a GTK project) called Subsurface. It is a SCUBA dive log and planner and was initially developed by Linus Torvalds (who happens to be a diver). He handed maintenance over to Dirk Hohndel.
It is written in Qt, has both desktop and mobile software, and runs on Linux, Mac, and Windows. It is, of course, open source, so perhaps taking a look at their code might be helpuful?
github
main website