Ask HN: Which came first? OpenStep on PPC? Or the MacOS UI on a NeXT derived OS?

I've been playing with OpenStep in a VM lately and it got me wondering what the transition from OpenStep on Intel/Sparc/NeXT hardware to Rhapsody on PPC was like.

Were there builds of basically stock OpenStep 4.2 running on PPC Macs within Apple on the early days? Were there builds with the Rhapsody UI running on Intel only while the rest of the OS was still being ported? Were these both happening at the same time in the same codebase?

I figure someone on here should have some inside information ;)