The big news is that Lego Batman director Chris McKay has been brought on board to direct this thing. That's a good sign, that fact they've picked a man who just had a big hit with a Batman-themed comedy to help a DCEU Batman spin-off gives me hope that we might get a film about Nightwing and not Batman-lite.
Because the thing about Nightwing is, despite the dark and brooding costume, that he's fun Batman. He's driven by his parents' deaths just as Batman is but he's actually managed to process his trauma and build a life outside the war on crime. Yes, some of that life is decidedly unconventional like the fact his best friends are a team composed of the other first generation kid sidekicks but... actually, that's not a bad place to start.
There's a fantastic issue of Nightwing where he's moving into a new apartment (in Peter J. Tomasi's run, I think) and the other Titans are just there helping him move. The Justice League don't do that sort of thing for each other. When the League meet up out of costume its either business or a really important event meant to promote bonding but the Titans just meet up to hang out randomly.
So, yeah, Nightwing is the Batman who has fun with his life: he hands out with his friends who are all superheroes, he leaps of tall buildings and survives instead of falling and dying like any normal person would, he grew up driving the Batmobile! That's fun!
Unfortunately, a large segment of fandom who have an outsized influence on the way DC thinks about their adaptations. There are a lot of people who are wrong and think Dick Grayson is too silly a character, that the whole Robin legacy is a terrible perversion of the Batman concept and must be expunged. Its a contingent of fandom that got a lot of unfortunate traction out of the whole mess that was the Batman and Robin movie.
So I'm kind of worried that instead of the fun-loving and emotionally healthy character I just spent a couple paragraphs describing what we'll get will be closer to this...