I mean... Halo is a perfect game for Battle Royale
Drop in drop pods on a huge map on a Halo ring with different environmental zones
Have fallen Covenant cruisers, Human fortifications, Forerunner caves, Forrest, snowy tundra, etc.
Have ghosts and mongooses in the level.
Scattered weapons to pick up.
They could even put in some minor AI to fight like grunts, etc.
And it would feel completely different than Apex or Fortnite.
I see some of you making the same complaints like the one I saw in the Apex Legends pre launch thread. "Wow another BR!? Stop chasing the trend" but Apex had a Battle Royale that felt completely different than any other before it.
If 343 feels like they can do something different and special with this they should go for it. Battle Royale is just another game mode like CTF, TDM, etc. Doom, Call of Duty, and Halo all have the game modes but they all feel different than one another.