I got it, thanks.
I've managed to disable Caps Lock with this command: gsettings set org.gnome.desktop.input-sources xkb-options "['grp_led:caps', 'caps:none']"
Then, to assign Caps Lock for input language switching within this Gnome framework, internet suggests three options. I've discovered, though, that none of them work:
gsettings set org.gnome.desktop.wm.keybindings switch-input-source "['VoidSymbol']"
gsettings set org.gnome.desktop.wm.keybindings switch-input-source "['0xffffff']"
gsettings set org.gnome.desktop.wm.keybindings switch-input-source "['Caps_Lock']"