I mean, we absolutely could test this experimentally, depending on the nature of these hypothetical beings.

For example, you could give multiple participants these mushrooms. Bring them into a sealed room one by one. Ask them to report the number of tiny beings around them. Ask them to politely ask the tiny beings to remain where they are.

Imagine if you cycled ten participants through, and each told you there were precisely 11 little humans in the room. With simple methods like this, you could apply statistical hypothesis testing to the results and see if the success rates differs significantly from chance. You absolutely could do real science on this. Science is perfectly capable of testing certain kinds of supernatural claims. Science would have a very hard time trying to determine what happens after death, if anything. But invisible tiny people inhabiting our reality, that we can miraculously see if we do one very specific thing? That's absolutely testable using the scientific method.