Actually, NeXT did just that. OPENSTEP ran on Mach, Solaris, HPUX, and (amazingly) Windows NT. It didn't make a difference for NeXT's market share.
NeXT was acquired by Apple. 6 months later... Jobs was in charge, and history unfolded.
NeXT was acquired by Apple. 6 months later... Jobs was in charge, and history unfolded.
But does/did Solaris have anything worthwhile to offer over BSD/Mach.