I have a 2016 with the non-touch radio. If I got the updated 2018-2019 touchscreen radio would that just plug and play? Logically I would think it would hook right up with 100% functionality since there is really nothing different between the 2016 and 2018-2019 models.
Based on what I saw in the wiring diagram for a 2016 Frontier with a base non-display radio: You can use a 2017 through 2020 Frontier display radio, but you won't be able use steering wheel controls, Bluetooth, in dash USB port ( if you have one) without rewiring of those features.
Radio power, speakers and illumination will work - and should be plug and play.
If your truck had originally come with a display radio, it would have the correct wiring to upgrade to a 2016 - 2018 Frontier display radio but not 100% correct for 2019 - 2020 Frontier display radio.
FYI: The 2017 and 2018 non-navigation radio has a display, but is not touch-screen. The 2019 and 2020 non-navigation radio is a touch screen radio.
If it were me, I'd be looking at
aftermarket radios.