I have the Xbox gamepass, and therefore was able to download Halo MCC basically for free. However, I had heard that within the MCC one could also obtain Halo Nightfall for free as an expansion with it. Is this true for players who obtain the MCC through the xbox game pass?
Every physical copy of the game came with a code for Nightfall. I’m not sure how it worked for the digital version (ie., if they received a code or got instant access), but those who purchased the game digitally also got access to Nightfall. Based on that, I’m inclined to say you won’t have access to Nightfall as it’s a separate thing.
If you want to test it out though, you can download the Halo Channel app and try to watch some Nightfall videos. Assuming your Game Pass subscription is valid, you would be able to watch the videos if GP subscribers are given access to Nightfall. If you cannot watch the videos, then you don’t have access to them through the Halo Channel app.