Avoid metal stuff while soaking and don’t add salt before they’re cooked.
It can harden the hull.
You may add some sodium bicarbonat to soften the hull but you need to experiment with the cooking time.
A pressure cooker is nice but you either need to calculate in the time it needs till you can open the pot.
Or you take the easy route and cook them till they’re done and you terminate the cooking process by cooling the pot in water.