Interesting thing I learned: Once you die the biome in your intestines massively contributes to processes that breakdown your body. That’s why decapitated heads are often in much better shape then the remaining body, especially if the surrounding environment is generally conserving the body, such as is the case in dry mountains or bogs.
From my understanding of the Buddhist process described here, the ritual often begins days or weeks before death, and includes exclusive consumption of substances like plant tars that dramatically reduce the presence of gut bacteria, and that this effect rather than anything supernatural is what most attribute to the most significant decay processes being temporarily inhibited - there's no gut bacteria left to decomp…
I can’t say what the actual process involves with too many details because it’s not appropriate to share with outsiders, but it involves meditating through sleep, which is considered a similar process to death.
The people doing this are good enough to practice through the night that they recognize a certain part of the death process and temporarily abide in it. When they stop, they die for real and their body decomposes.