Porting to newer Unity

How difficult would it be to port this game to a recent version of Unity, say, 2019.1 or later? For the [modified accessible version of this game](https://github.com/AccessKit/the-intercept) that I demoed at my NarraScope talk, we kept using Unity 5.3.4f1. But we'd like to focus our work on newer versions of Unity, while still being able to demo with a real (if minimal) game, i.e. not something that my colleague or I put together just for the sake of demoing accessibility.