After gruelling through all games on LASO, I loaded up Infinite when it released and I got nothing for my effort. Is this seriously how you’re going to do things 343? You’re going to ignore people’s efforts and stuff all the armour in the store? That’s gut wrenching. You talked a big game on being able to unlock legacy rewards, unlock armour in the campaign and through events. But most of the Mark VII armour has been in the store and the store ALONE. Which you said you would not do. This is an awful way to keep your fans around, because they won’t stick around when you take one main aspect away from them and lock it behind a pay wall.
I don’t remember them ever announcing any Infinite reward for laso
You get a nameplate for completing the legendary campaigns in MCC.
Completing LASO did get you some MCC achievements though 
One important consideration is that it’s quite uncommon that you will get rewarded for something done i video game A on video game B. If I’m not incorrect, the only Halo Infinite reward that are unlocked by completing a task in a different game is the Watchdog Armor Coatings which are unlocked by reaching SR152 in Halo 5.
Something else to consider is that LASO completions in MCC does not go unrewarded. The main rewards for the LASO completions are achievements, nameplates, playlist completion indicators and the LASO completion icon for the respective games which should suffice.
You get an emblem for doing MCC on legendary.
Thanks for the information. By the way, which emblem do you get for completing this task as it’s quite difficult to keep track on the unlock requirements for specific items due to the unlock requirements being hidden after you have unlocked the item?
Collection Conqueror nameplate.
Image below (remove the spaces)
https: //tiny url .com /444n82e7
Thanks for providing a screenshot of them emblem. If I’m not incorrect, it’s the Mark VI which falls under the Legendary classification.
343i never set the expectation that there would be anything for completing the games on LASO on MCC.
The only reward they announced would be there was for players who reached 152 in Halo 5.
You set the expectation yourself, that’s kind of on you.
I got all 700 achievements in MCC, I don’t expect anything for that. And guess what - we didn’t get anything for it.
Yes, it’s a Legendary nameplate 
I don’t believe 343 ever announced anything for this, but more to the point, remember;
This is a beta and the game will still be far from finished even at launch. That much is very clear. I mean, co-op campaign and forge won’t even be available until March of next year. I think it’s very clear they wanted to launch early and keep working on the game while they could get feedback from people playing it. I like that, personally, and I think in a year we’ll have a really outstanding game if they keep up working on it; people just need to understand that the game isn’t finished right now.
So, on that note, they may have legacy rewards you can get, but they definitely won’t have that sort of thing in the game already when the game itself isn’t even finished.
Bragging rights?
Some of us did LASO runs before their were even achievements for it. Where’s my cookie!?