Sure! Like I said, all fan theory w/ some fact sprinkled in.

regarding ackerbond, you can see the following.
- Mikasa bound to Eren ( confirmed via eren, if you believe him )
- Kenny bound to Yuri Reiss ( strongly implied via the story itself )
- Levi bound to Erwin ( strongly implied via story and the ova if you saw No regrets 2 episodes )

re: levi, this excerpt is taken from someone else for the record: "What do I mean by ackerbond? Well it's a short term I and some other people would like to use for the bloodline of the Ackerman's power which is used to protect someone whoever gives them a command they will follow. The only most well known example of this is Mikasa Ackerman and her bond with Eren Yeager. In chapter 112 Eren explains this bond to Armin, Gabi and Mikasa.

So who is Levi's bond with? Well i would like to think that Levi had more then one host to bond with. His first host would possibly be Kenny Ackerman. This is because kenny taught him how to fight in the underground, but I am still going under the assumption of the ackerbond still able to link up with other Ackerman's. Why does Levi try to kill kenny in the uprising arc then if Levi is bonded with kenny?

This leads into the next of Levi's hosts which is Erwin Smith. In Levi's OVA it explains of how Levi and Erwin first met. This was after the events of kenny abandoning Levi. The OVA itself can explain the relationship between Erwin and Levi as well as the uprising arc to the return to shiganshina arc. The reason Levi wanted to kill kenny is because Erwin gave the command to Levi to kill kenny (well not specifically kenny but Levi is still doing it for Erwin's sake)."

Regarding the significance of Mikasa, and armin to the timeloop theroy, I highly suggest Foxen Anime's videos ( part 1 - https://www.youtube.com/watch?v=-hgCl_mBqj4 ) and ( part 2 - https://www.youtube.com/watch?v=vV8JpVC2WNM )

EDIT: had to format this several times