There has to be a clear motivation for the project.
If the motivation is to use the new hotness than focus the project on that. Then setup the project in a way to properly gain familiarity with the new tech.
Whereas if motivation is a hot new idea and you want to see it to market, it is typically safer to use a tried and true stack and gain the joy of the wins of seeing the project advance.
My would recommend not tying a single project together with these two disparate goals, unless you plan on leaving one by the way side to see the other succeed.