Stellarium Mobile doesn’t seem to be FOSS which is weird because Stellarium uses GPLv2.
Their issue tracker has a bot that says:
This site actually does not discuss the Mobile version. Please use its own feedback system: https://www.stellarium-labs.com/support/
It clearly says iNOME O.
GNOME OS is a distro for testing out GNOME technologies and isn’t intended for daily use.