Can I just point out that pretty much all of these options, including guix, are things that were invented well _after_ nix was established as its own thing?
(aside from Haskell and Scheme themselves, of course)
I don't think you need to worry, I'm sure that who's familiar with PureScript also knows it's more recent than Nix.
Those PureScript records tho...
Purescript cannot type a record merge or join. Haskell with type families can, but the syntax would not be very pretty.