The "empty grey screen" is probably the default background of an empty X11 server without a desktop environment running.
Press Ctrl+Alt+F1 to switch to a text-based login prompt.
Log in, enter
cd /var/log to move into
/var/log directory, and then enter
less dnf.log. If it does not allow you to read the file, use
sudo less dnf.log instead.
Hopefully, the tail end of this log file will list the names of all the packages you mistakenly removed. Make a note of all of them: the list may include some packages that are not named like "gnome*", as they might have been removed because they depend on one or more of the "gnome*" packages.
Use commands like
sudo dnf install <package name> <package name> <package name...> to re-install the removed packages. Once all the mistakenly removed packages have been re-installed, reboot the system with
sudo shutdown -r now. After the reboot, if you managed to reinstall all the packages you removed, the system should be as it was before the mistake.
Unless you stored your data files somewhere you shouldn't, removing any packages should always leave user files and configuration files in place. Reinstalling the same packages should automatically use any existing configuration files for them, if available.