$ locate mimeapps.list
/home/memo/.config/mimeapps.list
/home/memo/.local/share/applications/mimeapps.list
/snap/core/3440/usr/share/applications/mimeapps.list
/snap/core/3604/usr/share/applications/mimeapps.list
/snap/core/3748/usr/share/applications/mimeapps.list
/usr/share/applications/mimeapps.list

$ for f in `locate mimeapps.list`; do grep -i nautilus $f; done
inode/directory=nautilus.desktop
application/x-gnome-saved-search=nautilus.desktop
inode/directory=nautilus-folder-handler.desktop;
inode/directory=nautilus.desktop
application/x-gnome-saved-search=nautilus.desktop

$ for f in `locate mimeapps.list`; do grep -i dolphin $f; done
<blank>