It sucks to type, but I'm not even fully convinced that Prime 4 is still happening.
It's been 5 years since Prime 4's development was restarted and we've gotten radio silence in the interim. Games take a long time to develop and part of this timeframe can be chalked up to COVID, but that's still a very long time for AA game to be developed. Jeff Grubb says Nintendo wants assets by this month, but his source for this was the guy who told him about Epic Mickey Remastered, a project that would theoretically be completely disconnected from both Nintendo and Retro Studios beyond being announced in a Nintendo Direct. There's a greater than zero chance it's a "I have one true piece of information, but I'm going to throw in something juicy that I've made up" source, which aren't common but aren't unheard of.
I hope I'm wrong, though. Metroid Prime fans had to go through a full decade of waiting for a Prime 4 announcement and now they've had to spend nearly as long waiting for damn footage. At least rip off the band-aid if the project got cancelled, Nintendo.