I'm sure you already know it doesn't contain spotlight itself, which belongs to Apple.

There exist equivalents that have exactly that same functionality as described above. I don't know what GNOME uses, but KDE's krunner searches system settings, user files and applications, bookmarks, browser tabs, solves arithmetic and unit conversions, does spell checking, searches the web, searches active windows, applications and workspaces, etc.. It's configurable with many plugins available. I expect GNOME's system works similarly.

I'm specifically speaking of Ubuntu's version of Gnome, I guess. Press the Super key and a search box appears, a la MacOS's Spotlight. This is how I open apps. There are likely nuances about what is searchable, but in practice it feels the same to me.