I would like to begin by thanking CamdenG with the opportunity to debate this topic, which is a refreshing change from the perennial topic of "Does God exist?" Some may perceive these as practically identical, but I can assure you that there is a clear distinction.
Let us suppose that instead of arguing about the existence and the provability of the existence of a creator deity (commonly referred to as god), we substitute the subject of a sock on my left foot (SOMLF). Such a thing, as described, either exists or doesn't exist. The question of whether it exists is a simple enough answer: one could use any variety of instruments to determine whether there was in fact, a SOMLF, though the simplest and quickest would be the naked eye. The absence of a SOMLF can be demonstrated by the same means. The concept of a god and whether he/it exists is more complicated by a multitude of factors, of which I will list a few.
1. Location. Where the SOMLF is definitionally always located on my left foot, there is no specific place that god is defined to exist. The problem of location is disproportionately burdensome on the claim of nonexistence than it is on existence. If I were to ask the question "Does a sock exist?" It could only be disproven after searching the entire universe, while its existence can be almost instantly proven by looking down at my personal SOMLF, or by running to the nearest laundromat.
2. Tangibility. While many theologies describe god in some capacity, their descriptions vary wildly. Some describe him as having a physical body like humans, and even give him characteristics such as 'bearded' and 'male'. However, the theoretical concept of deity as "omnipotent, omniscient, and the creator of all" as Pro puts it, is sufficiently vague to leave other characteristics open to uncertainty. If, for instance, a goldfish were to tell you that it were god, you would test for these 3 characteristics rather than whether the goldfish had a beard.
Before I go further, I must address Pro's claim that no true knowledge can be held, or in their words, "there is nothing which can be truly unquestionable". In short, nothing can be proven. This strikes me as a rather disingenuous claim, as Pro's entire argument is predicated on proving the truth of their argument. It also differs from the typically held definitions of words such as knowledge. In philosophy, knowledge is often defined as being a justified true belief. One can have a belief that they have blue eyes without it being knowledge. They could even have a true belief that they have blue eyes, without looking in a mirror or ever being told their eye color, simply by chance. However, you can only have a justified true belief by looking in a mirror and actually observing the fact of your blue eyes. This discrepancy between your beliefs and reality is sometimes referred to as the Map and Territory. You could just as easily say "we don't know that 1+1 = 2" yet tens of thousands of years have gone by without a single recorded instance of getting any other answer. While a hundred percent confidence is technically impossible in Bayesian probability, you can reach sufficiently far into the repeating decimals of 99999999 that there is no practical difference.
Given our improved understanding of knowledge, we can now get into the weeds on how one would would going about proving the existence of a deity. As we discussed before, there is a much higher burden to disprove something than there is to prove it. You must search literally the entire universe to disprove the existence of socks, yet it only takes a single sock to undo all of that work. So first, let's assume we find a potential deity, whether they declare themselves or we find them in our search. We're already almost done, we just need to run through some authenticity tests to verify that it is a deity.
Test 1. Omnipotence
Omnipotence is generally characterized as the power to do literally anything. Vaporize a planet? Child's play. Cause a star to supernova? Even humans could probably do that with enough nukes. A true test of this initially seems impossible, especially as the scale seems increasingly dangerous in that direction. Most prefer to look for violations of the known laws of physics. You could start with some ridiculous request, like making a hotdog appear in the hand of every person on the planet, or a demonstration of FTL signalling. No single test would be conclusive, as our understanding of the universe is incomplete, and even relatively simple changes like transition from Newtonian to Einsteinian physics took decades of testing to be confident. But such a huge problem that any one of these experiments would bring up would be enough to draw thousands if not millions of researchers, who could eventually decide if the candidate possesed true omnipotence.
Test 2. Omniscience
This test also involves a breaking of the laws of physics. Knowing everything is simple in concept, you merely need to simulate every single particle and force operating in the entire universe in perfect fidelity for the entire lifespan of the universe. Mind reading would be a simple first test, but would likely extend to stuff like prediction of the future, resurrection of dead people to obtain testable lost knowledge (Harry Houdini, for instance, left a special passphrase with his wife to test whether a medium could actually communicate with him after he died), and FTL signalling again (in this case the application would be describing events lightyears away before light could possibly reach Earth, which could be compared to imaging as it reached earth)
Test 3. The Creator of All
Actually verifying that the omnipotent omniscient being that we have so far tested created the universe seems impossible, as far as I can tell, but by being omnipotent, it definitionally has to be at least capable of creating the universe, even if this particular universe that we live in was a gift from its grandma.
In summary, in the scenario where a god did exist and decided to prove it to humans, it would be definitionally capable of doing so, by dint of its omnipotence and all that. The fact that we have not seen one do so is unrelated to the resolution, though it may be interpreted as such a being either not existing or being unwilling to do so.