This GNOME shell extension disables the workspace switching animation. All other animations, including the trackpad swipe to change workspace are preserved.
Switching workspaces with keyboard shortcuts happen instantly, akin to a window manager like i3.
https://extensions.gnome.org/extension/4290/disable-workspace-switch-animation-for-gnome-40/
Clone the repo & copy the folder instantworkspaceswitcher@amalantony.net to \$HOME/.local/share/gnome-shell/extensions:
git clone https://github.com/amalantony/gnome-shell-extension-instant-workspace-switcher.git
cd gnome-shell-extension-instant-workspace-switcher
cp -r instantworkspaceswitcher@amalantony.net/ ~/.local/share/gnome-shell/extensions
Log out of your current session and log back in.
Open the Extensions app, and enable the extension.