Funny enough that you say that! The company that I really like for these types of products, Therasage, has done that exact thing except for ultrasound.
https://therasage.com/collections/therapro-pemf-infrared-red-light-pad
That's the one we bought for the PEMF mat. It's got infrared sauna, red light and PEMF all in one, plus a Tens attachment so you can do the whole kitchen sink at once hahaha. We haven't tried ALL of them at once, but it's going to be something that we will eventually do.
Wild, a true combo therapy. In California I was able to get ultrasound and tens combo at the chiro which was AWESOME! Washington state doesn't allow it for some reason. I bought used gear from a chiro in Idaho so have the tools but have been keen on newer tech for a while now.
Yeah I've heard of that being used for joints like knee I believe.
Washington has some bizarre rules that's for sure