My guess as to what Trump might have said to Xi at Mira Lago:
1. China wants to avoid a rich, militarilyy powerful, unified Korea on its doorstep.
2. USA/SK want a stop to nasty NUCLEAR threats
Therefore:
1. China withdraws support for NK
2. USA knocks off NK
3. China installs non-nuke puppet regime in new NK
That would seem to me to “make a deal”.
About time.