I have exactly the same question but the reply from Jesse at Dell does not help me much.
Would it be possible to have a concrete model of pen from Dell and/or others that is compatible with the Latitude 3379? It seem the PN 338, 556, 557 are not compatible...
Something like this will work
Note that this is a touchscreen model - it's not a digitizing tablet, so a pressure-sensitive stylus is not going to work with it. For that you'd need a true tablet - like the XPS9365.