From his interview with Chris Van Vliet embedded above:
“I get the question a lot: when are you going to the main roster? And I absolutely hate that question. I absolutely hate it so much. I get tweeted a lot, people say ‘I can’t wait to see you on the main roster.’ Like, you ARE seeing me on the main roster; NXT IS the main roster. I do believe Raw, SmackDown, and NXT, those are the three brands. I think people can come from Raw or SmackDown to NXT, I think people from NXT can go to Raw or SmackDown. I think it is very interchangeable. Obviously there are different worlds, I guess there, in people’s minds, but for me this (the NXT championship) is my main roster title, this is my main roster moment.”
Gargano spent some time on Monday Night Raw this year but Tommaso Ciampa’s injury led to his heading back to NXT. If we’re to believe him, this isn’t an issue because he’s fully committed to being an NXT star and nothing more.