And maybe more importantly, LAN multiplayer actually exists in case of ISP problems, server outage, or trying to play the game in 20 years when the official servers are long gone.
AFAIK the same has worked in Halo: MCC for as long as that's been available on PC. I've certainly been cross-playing my replay of the campaigns, rotating between PC, Xbox One, and XSX based on whatever I'm in front of at the time.
It is nice that Microsoft finally acknowledged a few years ago that their consoles are Windows devices that have USB ports and stopped disabling keyboard/mouse support. The idea that console users were banned from better FPS input for years was just nonsensical.
Now if only we could get them to mandate keyboard/mouse support instead of making it optional. There's no good reason to force console players to not be able to aim properly.
https://www.pcgamer.com/halo-infinite-will-let-you-use-your-...
And maybe more importantly, LAN multiplayer actually exists in case of ISP problems, server outage, or trying to play the game in 20 years when the official servers are long gone.