It wouldn't be Linux if there weren't a dozen other ways to perform any given task. Flexibility is built into the system with Linux, so while GNOME Software provides one easy way to get apps, there are lots of other ways, including install scripts, install wizards, AppImages, and of course compiling directly from source code. You can get information on all of these install methods from this Linux eBook.
A guide to installing applications on Linux
Download this eBook for tutorials on the different methods for installing applications on Linux.
What to read next