Just wondering is it possible to turn fermented sugar water with an abv of around 15% into moonshine by freeze distilling it. Also wondering if i would have to worry about methanol when using this technique
You are right to be concerned about methanol it is a very nasty poison. You are at a lower risk of building up a dangerous level of methanol from all grain fermentation as it produces roughly 1/10 the amount of methanol as grape or fruit fermentation. I don't know about sugar water fermentation but as it lacks any pectin or cellulose it should be cleaner regarding methanol than grain.
In whiskey production which is a grain fermentation they drop the heads, and tails from the distillation, as the heads contain methanol and the tails off flavour longer alcohols. You do not have this luxury in freeze distillation.
The level of methanol can be reduced by choosing a clean fermentor, the right yeast will ferment with lower methanol levels. Also good temperature control can also be used to reduce the levels.
Unfortunately testing for methanol is not easy or simple you can use Sodium Dichromate and Sulphuric Acid, or send a sample for Gas Chromatography or Mass Spectroscopy.
When thinking about brews like the famous Tactical Nuclear Penguin or Sink the Bismark, just remember that Brewdog will have sent these off for lab analysis before putting the product out for sale.
All of this said you should be OK, but it is right to be concerned about such things and to understand the dangers.
If you do go this route, you are probably best to stop after a couple of rounds of freezing as you get diminishing returns after that.
This topic of testing is discussed further here.
Methanol comes from cellulose & pectin, which for homebrewers means fruit. So, you shouldn't have any problem there.
Freeze distilling should increase your alcohol concentration, but I don't know how that would taste. Moonshine in my country is still made more-or-less like whiskey (corn, grains, etc). Fermented sugar is more of rum making thing.
Q1) No. you won't achieve moonshine levels of alcohol with freeze concentrating without the ability to super freeze. Ethanol works like an antifreeze.
Q2) answers in other posts
If one were brewing with yeast and sugar then one would not have to worry about methanol. methanol production only gets problematic when using fruits, especially stoned fruits, as a source of sugar when fermenting
Freeze distilling can be performed multiple times on a standard mash brew to obtain a strong alcoholic drink (eg BrewDog's "Sink the Bismark" - 41%ABV). Whether that counts as "moonshine" is up to the consumer to determine.
However this question may be off topic for this particular brewing forum.