> Start by explaining how there can be any experience at all after an hour without oxygen to the brain.

Some cells are still technically alive after 1 hour mark in the sense that there is no necrosis and cell membrane is still operating. This depends on cell type and nourishment - for example cells that have high amount of CoQ10 can live longer etc.

In any case, brain is definitely NOT 100% dead in a sense that ALL of its cells are necrotic which might explain why it is in a dream like state.

Also, I doubt 1 hour mark is regular thing in NDE.