I understood LiFePo4 is pretty safe and innert.

Sodium I saw some reviews where it expands a lot during charging and long term safety is not as conclusive

Why do you see sodium as an easier choice?

The main fire risk with lifepo4 is the connectors, wires, bms and shut off being suitable for high amp. That would be a risk with anything if not built properly, even without batteries if you wire your house with wrong awg wires