The topic Haruna player - start in fullscreen mode? contains a solution (create a window rule) for people who use KDE but it is not available to me as an Ubuntu Gnome user. After starting a video I am able to toggle to fullscreen using the f key but that is a pain to have to do every time.
I was very disappointed when I checked the box in Settings>General>Start in fullscreen mode as it then would not display at all when the video was started from within the file manager, Nautilus (I have Haruna set as my default video player). When Haruna itself is started (after selecting the fullscreen check box) it would open but it still defaulted to the same small window size it had been displaying. I seem to remember seeing others on the web also having no luck with that setting but I didn’t notice what linux distro or desktop they were using. I tried other unsuccessful ideas such as using the config file to set the fullscreen attribute to yes and creating a command that I set to run at startup to either set or toggle fullscreen. I have experienced the same behaviour in the snap, the flatpak and the native app.
Any suggestions? If no resolution should I report as a bug since the fullscreen setting available in the app does nothing or do I forfeit that right because I am using GNOME (hopefully that is just humorous and not a real thing)?