Is using the word Maybe just a weasel word to get around the burden of proof?

The earlier use of the words "maybe "or "assumption" resembles the thought-terminating cliché, "I'm entitled to my opinion" because we are programmed to respect other people's opinions even when they have no basis in fact. So, yes, it's a dodge, but hardly a fallacy. It simply doesn't qualify as a valid answer either.

In a debate, the answer to such puerile nonsense is, No, you're not entitled to your opinion you're only entitled to what you can support.       

Person 1: I'm saying that yeah the supposed evidence points to them working but also I may challenge that idea and say what if the Vaccines were fabricated.

There's your deception right there. This is a clear switch from a discussion about the efficacy of vaccines to a nonsensical and irrelevant supposition, but what if the vaccines were fabricated? So, what if they were? In fact, the vaccines were fabricated, but what possible relevance does that have to their efficacy? So, it is clearly a red herring, an appeal to ambiguity, or maybe even an ad hoc rescue. Fabrication has nothing to do with it. 

Or, are they implying that the evidence was fabricated? If that's the case they still need to support the claim. That's the great thing about evidence as opposed to wild speculation and conspiracy theories. 

I'm saying that yeah the supposed evidence points to them working 

Okay, clearly Person 1's argument reflects their overall ignorance about the evidence-based debate in general.

Having evidence of the efficacy of vaccines increases the probability that they are effective, it does not decrease that probability. So merely introducing conjecture, alternative theories, or other unsupported possibilities does not increase the possibility that they don't work it only decreases it.  In any debate between a theory supported by evidence and precedent and a theory supported by none, the former is always more likely.

"maybe" just means he does not know for sure. It is more of a question than a statement of fact. It is also a tactic to seed doubt in something. Sounds like he is trying to say something and at the same time leaving a way out for himself " I never said it was true so you can not hold me to it.". What I would call political talk. This is where a little critical thinking goes a long way.

An "outlook" is still based on reasoning—good or bad reasoning. Forget about "burden of proof." Simply ask, "on what are you basing this 'outlook'?"

Person 1: I can make as many assumptions as I want with the vaccines not working, I never claim them to be true.

Yes, person 1 can claim whatever they want. They still need to provide evidence for those claims if they wish to assert them as true. If not, then they need to explain what the purpose of those claims is.

I'm saying that yeah the supposed evidence points to them working but also I may challenge that idea and say what if the Vaccines were fabricated. You can't pull out the logic fallacies card its just my outlook. 

Ah, okay. The person might, in this case, be making claims they know are false as part of a 'what-if' argument where they explore what would happen if they  were  fabricated. This is a counterfactual conditional and there's nothing wrong with it on the surface, as long as it isn't being used to advance the idea that they were  actually  fabricated.

Following from this there'd be no fallacies, but quite a bit of poor communication!