I don't have any personal experience with using a touchscreen on a MKR WAN 1300, but certainly it's possible to do so. You only need to make sure of a couple things:
That the libraries you're using for the touchscreen support the samd architecture of the MKR1300 (and you will find the popular libraries for the common touchscreen displays do).
That the touchscreen will not subject the input pins of the MKR1300 to voltages higher than 3.3 V. If you have a touchscreen that outputs 5 V then you will need to use voltage dividers or level shifter modules to reduce it to a safe voltage.
Those two things apply to any hardware you want to use with the MKR WAN 1300.