Fork `basement`? As `baseplate`?

How about the fact that ghc-prim literally only consists of GHC internals and primops? Why would you expect MicroHs (or any Haskell compiler that isn’t GHC) to support it?

For what it’s worth, packages shouldn’t depend on ghc-prim in the first place and the majority of those who do, don’t need to and could use modules like GHC.Exts instead.

As for MicroHs support of 32 bit platforms, the MicroHs CI also runs on 32 bit architectures, so everything should work.