What you are losing is what you are gaining ; I for one embrace the minimalism of Gnome (even macos feels, looks bloated next to Gnome). There’s only 2 extensions that I add, and they are the vainest ones: the Spinning Cube and the Wobbly Windows.
No, there’s one more: the gnome implementation of kdeconnect, so useful to link your phone to your PC.
Of course KDE has great, great software out there, you shouldn’t be loosing anything by switching, so that’s where I use flatpaks, to not have to pull all of KDE libs on my system over the gtk ones: kdenlive comes to mind.
Embrace the zen. Drop the very idea of spending a week to fine-tune your Desktop to your liking - a gnome install is finished in about 5 minutes, including setting up the best wallpaper ever, the competition-winning KDE 6 Peaceful Tree default background.