As far as I understand, other games have been using the UE for Switch in past.
I am going to say this, SMTV looks absolutely stunning, and that considering that this is coming from the same company responsible for Persona 5, I am almost thinking this will be a fascinating game to look at.
And as another thing, it shows confidence to me on the Switch's potential graphical fidelity and also how a company as notable in the industry like Atlus is wanting to make their big fifth game of the SMT series an exclusive for Nintendo. It's fascinating, and it makes me interested on what other companies in Japan and internationally do with the hardware of the console.