Robin Rebiere has shared a free tool that lets users use shortkeys for favorite nodes, up to 36 shortcuts, featuring an option to save each time you press Enter in Substance Designer. Please note that it works only in the Substance window.
You need to type the name of the desired node and press the previously selected key, left-click at the same time, and your node will appear. Enabling the checkbox will automatically save your file each time you press Enter.
The toolkit will “create a .txt to store your shortcuts and each time you will use one it will press Spacebar, write the name of your node then press Enter.”
You can learn more and get the tool here.