LifePo4 is definitely the safest mass produced battery but there is still a thermal runaway risk if there’s a short or a serious overcharge for a long period of time.
If safety is the ultimate goal then Lithium Titanate Oxide (LTO) cells are the supposed to be the safest with zero thermal runaway and cold temperature charging. they’re also excellent at fast charging and discharging. The only problem with LTO is the price and the density is much lower than LifePo4. If they can find a way to match LifePo4 in density and cost to produce then I think LTO would get regulated and the others would nearly be regulated out of existence. Enough Tesla fires already.