Okay, I wanted to expand on all of the things touched on in that Reddit post I linked above. I went and broke down all the new footage and here is what I found:
Sandra (Mana) helping(?) Tai (Nuku) with the chicken cages.
Unsure who is in this photo, however the blue waterbottle gives away that it is Nuku.
(From Left to Right): ?, Sarah(?)(Nuku), Zeke (Nuku), Troyzan (Nuku), Tai (Nuku), Brad (Nuku)
(From Left to Right): ?, Cirie (Nuku), Brad (Nuku), ?, Debbie(?)(Nuku),?
Brad (Nuku), ?, & Sierra/Andrea (Nuku/Nuku) celebrating after I'm assuming they won a challenge.
Water Challenge (Possibly Battle Dig)
Troyzan(?) (Mana), Sandra (Mana), Aubry (Mana) waiting pre-challenge. (Assuming this is pre-water challenge because of the red flag in the background, which matches up to other flags seen in the water-challenge shots).
Malcolm (Mana) competing.
JT (Nuku) competing.
Malcolm (Mana) & Aubry (Mana) competing.
Andrea (Nuku) diving into the water. (May be the first water challenge).
Caleb (Mana) wearing a correct Mana buff (not buff-o-matic'd -- has orange designs)
Cirie (Nuku) carrying an orange bag. Although considering necklace and clothes this may be from the Marooning instead.
Post-Swap Bucket Challenge
Michaela (Mana), wearing a buff-o-matic'd buff (designs are light red instead of orange) before the challenge. Note the green challenge props behind her.
Sandra (Mana), with Michaela (Mana) wearing a Nuku buff.
Sandra (Mana), standing in front of a green challenge prop.
Malcolm (Mana) & JT (Nuku), competing for Nuku.
Nuku Male, Michaela (Mana), ? competing for either Nuku or a third tribe. Michaela is wearing a fake-Mana buff.
Malcolm pre-swap with a sandy hand.
Ciera after competing in a water challenge(?)
Caleb in the correct Mana buff.
Tony with Sandra in the background.
I'd guess that Nuku wins at least the first or second Immunity Challenge from the celebration picture.
If the Battle Dig Challenge is the first Immunity Challenge (and only challenge that episode) -- Malcolm, JT, Andrea, Caleb, Michaela, Sandra and Troyzan can be ruled out as first boot.
Because these intro shots are generally only filmed during the first three or four episodes, I would assume there is a swap at the Final 18 -- probably from two to three tribes where the third tribe is green. Sandra, Malcolm, JT, Michaela all reach this point and are on Nuku as @galbi7892 pointed out.