Hello OrganisedLarder. I completely understand your caution about new gadgets, especially when it comes to keeping your food natural and chemical-free. A pressure cooker is actually just a sealed metal chamber that uses steam pressure to cook food faster, so no strange chemicals are involved at all—just pure water and heat.
When it comes to boiling eggs for meal prep, pressure cookers are fantastic because the high heat and pressure make the eggshells slide right off during peeling. If you decide to try it, place your eggs on the steam rack, add a cup of water, and cook on high pressure for about 5 minutes, followed immediately by an ice bath.
For more details on appliance safety and cooking methods, you can read more about pressure cooking basics.