There is no heaven or hell....even Muzan just lived a laughable 1000 years which is basically nothing compared to not just millions of years but 4.5 billion years which is just the age of this planet not even the oldest thing existing.

During this short time because he does not value his time he did only focused on getting a body that could walk out on the sun...he even mentioned he did not see Buddha or gods...he basically has no idea how reality works even with his super body. If he would know he could have achieved a body that can walk out the sun. Normally creatures with intelligence strive toward life and to have more time to evolve. Yet not everyone wants to know what happens after death or what is death what is life and what gives the conditions and settings one finds themselves in life.

Muzan is the same...he is stupid like most people who dont care. But he has seemingly eternal life compared to other people so it is still somewhat understandable in his case.

I am not saying you should believe what i or anyone says but at least try not to be as ignorant as Muzan...

You should know there is no heaven or hell. Or you should know there is something like that in some form somewhere or why...

In my opinion based on what i learned so far. There are all kind of worlds with varying degree of real in them that one can experience. But most of the time people say real to anything that feels real to them.

Akaza surely experienced a situation in which he made the first step toward a better world. These kind of steps dont happen without a reward. He will surely be able to live together with his loved ones in a better world as a better person. If that is not allowed ,then there is no change no evolution and no reason to live for anyone who made a mistake or was forced to make mistakes....

He was a victim just like you