Like Spotlight, Windows Start text entry, Gnome activities menu?

No. Searching in the current app menus. Because they are centralized and don’t have their own comportement. In MacOS you can activate the search in menus keyboard shortcut in any app, giving you a Sublime/VSCode-like command palette in any app.

Oh right, I remember that feature from Unity!

Apparently Fildem is a spiritual successor for Gnome.

https://github.com/gonzaarcr/Fildem

Have you tried Simon Schneegans awesome "Gnome Pie" application launcher, which lets you define your own pie menus?

https://schneegans.github.io/gnome-pie.html

Gnome Pie:

https://vimeo.com/30618179?embedded=true&source=vimeo_logo&o...

For his thesis, he also designed and implemented the elegant Coral Menu:

https://vimeo.com/51072812?embedded=true&source=vimeo_logo&o...

And the cool Trace Menu:

https://vimeo.com/51073078?embedded=true&source=vimeo_logo&o...

Simon Schneegans' Bachelor Thesis about Gnome Pie, the Coral Menu, and the Trace Menu:

https://schneegans.github.io/news/2012/10/10/bachelor-thesis...

Fly-Pie is his more recent wonderful work:

https://schneegans.github.io/news/2021/12/02/flypie10

Fly-Pie 8: New default dark theme and support for GNOME 3.36, 3.38, 40, and 41!

https://www.youtube.com/watch?v=j9t7hfkE_5w

Fly-Pie 10: A new Clipboard Menu, proper touch support & much more!

https://www.youtube.com/watch?v=BGXtckqhEIk

>Fly-Pie is an attractive marking menu for GNOME Shell. Fly-Pie 10 brings improved touch support, a new clipboard menu and a bunch of other new features!