I played and completed #HaloFireteamRaven. I would say that it is about 30-45 minute campaign. You do get some rewards in #HaloMasterChiefCollection & #Halo5Guardians for synching your GamerTag (via QR code) to your gameplay session (it logs you out once your session ends).

https://www.gamespot.com/gallery/big-name-franchise-games-you-might-not-have-played/2900-4815/