A space pod containing an astronaut drifts out to space and cannot be rescued. The space pod contains no insects, and the only bacteria present are those originally brought in by the astronaut. There is plenty of oxygen (assume 20%) and the interior is heated in the long term to 20 degrees C by a radioisotope heater.
The astronaut eventually dies through lack of food or water. His body is found many years later. What will the rescuers find? A body or a skeleton?
First I assume many years equals 10 years or more, although the presence of oxygen may drastically speed this up or it may interfere it is hard to say. Nobody was tried to figure out how something will rot in sealed but consciously oxygenated container since is basically does not exist without a custom built chamber.
Your main factor is humidity that is whether the pod has humidity control, if it keeps a human comfortable humidity you will have a skeletal mummy since skin and hair will survive but much of the body will desiccate. If you just treat it like a sealed container the body fluids breaking down will ramp up the humidity and you will just a have a pile of bones and rather disgusting soup. A sealed container is one way to rot down an animal carcass to get bones, it is called maceration and something that has been well studied. I have done it many times and a few years is more than enough to reduce a carcass down to a skeleton. Note depending on how long you wait even the bone may be damaged or destroyed although the restricted biota may prevent the final stages of this leaving you with extremely fragile skeleton remains.
I must emphasis the smell will be disgusting, as in even seasoned investigators will be tossing their cookies if they smell it. Almost nothing can describe the disgust of the smell of a human body rotting in a sealed container. Our brains have evolved to find human rotting flesh as disgusting as possible.