Woah! I'd love to see all those crosses, but not sure how many are possible? One thing I'd suggest is to check out the relevant cladograms (ie
Rhipsalideae) in order to learn how closely related two species are. The more closely related they are, the more possible it is to cross them. Here's another relevant cladogram...
Hylocereeae.
It would be amazing to have a Rhipsalis type cactus that produced fruits the size and sweetness of grapes. Hmmmm...a few months ago I bought Disocactus aurantiacus. Just now I learned that
the fruit is surprisingly large. But how does it taste??
A while back a friend offered me the fruit from her Epiphyllum hybrid. I went back home and couldn't help but taste it. I was surprised how good it was. I made the rather difficult decision to stop eating it and save the seeds, which I germinated and dispersed among friends. I have at least one seedling that I should really pot up.
Years ago I gave away my rather substantial collection of Epiphyllum hybrids. The flowers were too short lived to warrant the amount of space the plants took up. But I never tried any of their fruit, which I don't remember them ever having.