A. Apply software update to get new 2017+ MTC version?
the 17 and up cars have a completely different headunit, there is no available update to get that to that level as the hardware is completely different, as well as the entire center stack assembly.
B. Replace physical MTC unit with 2017+ version ... will it fit?
the 14-16 is 3 pieces, hvac, screen, radio unit. the 17 and up car is hvac control and an intergrated screen/radio module. fit? maybe. but it'll take more parts than just a radio. also, unsure if the connector lay out is the same. the network is different due to the whole center stack changing.
C. Replace physical MTC unit with Apple/Android CarPlay unit or 12.1" Android unit made for 14-16 Ghiblis?
feasible likely, but keep in mind that the instrument cluster depends on some data from the radio, as well as the radio setting and controlling vehicle functions.