Game developers could do it fairly straight forwardly but the demand for multidisplay functionality isnt really there. Supcom had a 2nd monitor option to render a 3d map but i cant think of any other games that do a separate function like that. Ac6 has a minimap? Fat chance getting something that cool and involved with a game you cant completely mod or make yourself though. Itd be really sick to see something like it on ac6 especially. I miss 4/4fa's HUD.

God, that would be awesome. I don't know of many games that natively support multiple monitors with different information, I think there was a space command game or something like that that could do something like this? I don't remember, it was many many years ago.

But on this topic, games should also support multi-screen splitscreen! I know next to nobody would ever use the feature because who on Earth plays local co-op on PC, but I saw a mod for Borderlands 2 once that allowed player 1 to be on one monitor and player 2 on another, and god that would be perfect for some modern games.

Rendering more screens is more demand on the graphics card.

Also, not everyone has multiple screens or their screens laid out in a similar arrangement and/or the same resolutions.

Beyond these though, there shouldn't be that much limitation to the idea.

I currently play Baldurs Gate 3 couch co-op split between two screens. There doesn't seem to be a way to do it natively, since it recognizes each monitor individually, but doesn't see their connections to each other. I have to do a borderless window and then drag one side of it to the other monitor.

Anyway, I wish there were more built-in options to spread a game across multiple screens. Years ago I used to play Rocket League across three monitors so I could see more of the field while playing.

Some games do support this functionality; typically flight or racing sims. Best of luck getting it running.