I grew up in AK, and have fairly extensive experience in the drug worlds of both interior & coastal AK (unfortunately)
Marijuana is legal, mostly high-grade & everywhere, although the dispensary system thus far is pretty lacking compared to other legal states.
Meth is also always available, reasonably priced & usually above-average quality...some people still do "home cooks" out there, it's more difficult to obtain the necessary precursors nowadays but it's not impossible...the small batch stuff seems to be sometimes better than the stuff that organized crime brings in but it really depends on who you're dealing with, obviously...the 1% MCs have a visible and notable presence in the meth trade in AK.
Cocaine and crack cocaine are also available but are overpriced and the quality is often very lacking.
Heroin is everywhere, expensive (compared to the rest of the USA) & has wide variations in quality. It's approximately 100% Mexican tar. Some of it is pretty good though. You may be able to find other non-heroin opiates but expect to pay out the proverbial ass for them (with the exception of bupe which is usually somewhat reasonable).
Psychedelic drugs like acid or mushrooms are also available (quite a few hippies live in AK) but the psychedelic drug scene is more "insular" and obscure compared to the wider drug market, and may be more difficult for a newcomer to access. It definitely exists though, fueled by Alaska's local hippy population & the students who attend the University of Alaska system.
The drug trade is pretty "decentralized" in AK...organized crime is definitely a "thing", especially in a market like Anchorage, but for the most part there just isn't enough profit incentive for doing business in a lot of AK. So the void tends to get filled with small time dealers who import from west coast connections (LA, Seattle etc) & junkies who sell a bit on the side to support their own habit (the worst kind of dealer IMO). I'm currently in the northeast USA and the difference between the dope trade here and the one in AK is like night & day. There are no "open air" markets in AK. You have to "know somebody" up there, but once you're in, you're in...you develop a few good phone connects and establish a reputation as a good customer and you'll have 24/7 access to drugs, just like anywhere else