I'm not sure if I would use that bowl for feeding , only because the sides seem a little high. Unless your beardie likes to climb up on the side to look in, I don't know.My beardie likes to look straight on in front of her at her food. Then again all BD's are different. Try it and see!!
As for it being a
bathing bowl for an adult BD, I would have to say no. If it's only 8" wide your BD would have to curl up in it(that is saying that your adult BD is at least 8" long).They generally prefer to lay out flat in the water as adults.