Dinah gets a LOT to do outside of the typical action stuff. Perhaps the most out of the Birds, from a narrative perspective. She’s definitely a major part of the film, and Jurnee is great!
What you need to know from Suicide Squad is in the film (literally, in some cases, there are a few very brief flashes back that use snippets) - and beyond that, it’s mostly just the premise that Harley’s breaking up with Leto’s Joker. You’re very free to not see a very bad movie before you go see this good one!
WHAT IS REALITY EVEN ANY MORE
Excuse me, I’m sorry, did... Germain did you just type what It hink you typed?
This is now the Black Widow Crew Hat Cinematic Universe.