rice and lentils will cook up in a rice cooker in half that time.

Adding 1 onion diced and 6-10 garlic cloves grated really amps up the flavor too. When pressure cooked they kind of melt into the bean broth

One thing I have been obsessed with is tomato bean soup. The recipe I base mine off is sopa tarasca, a Mexican dish that also uses a few ancho chiles. But you could use chile powder or omit that.

Anyways, I really like your idea of adding mushrooms and doing it in the pressure cooker. I might toss in a can of tomatoes and some onion and garlic. You could throw in other veggies too, like anything about to go bad. And add rice to really make it a meal. Beans and rice is so good when done right.

High pressure?

I have done dried beans in the Instant Pot several times to good affect. 1 hour at pressure seems a long time.