Windows 10: Cross play between halo 4 microsoft store and steam

At this time I have a buddy who is trying to get back into Halo. He purchased halo 4 on steam. And I would like to play it with him. I am a current owner of the full Halo franchise for the titles that were available on the 360 and even purchased the X one to be able to relive the MC days. I would like some assistance as to how halo 4 for pc through Microsoft store can be cross played with someone on steam.

:)

 

add games to steam store

I'd like to request that a few games be added to the Steam Store those being the Windows versions of Gears of War 1, Halo 1 and Halo 2. The steam community suggested it'd be best to contact Microsoft directly hence why I made this post.

 

Steam Friends cross play

OK So basically I got the pc game pass. Me n my mate wanted to play Astroneer. Now I bought mine on Microsoft n his on steam however in the xbox app where you download the games I could link my steam. But none of my steam friends appear online or even
on my friends list though it says the account are linked.

 

Steam and Microsoft Store (Play together?)

Recently I was under the impression that Gears of War 5 was only going to be available on PC (if and only if) you purchased it on the Microsoft store. Today I logged into steam (8/19/10)
and realized Gears of War 5 was available for pre-order on the Steam Store. This caused great panic because I had already purchased it on the Microsoft Store. When it comes to matchmaking/co-op play, does it seem like Microsoft Store purchasers and Steam Store
purchasers are going to be able to play the game together?

In short:

-Can Gears of War 5 players who purchased the game on Microsoft store expect to play with their friends who purchased the game on Steam?

Example: John has Gears of War 5 on Microsoft Store and Bill has Gears of War 5 on Steam...can these excellently named gentlemen play together online?