If I buy a Mac mini to run OpenClaw can I connect it to my MacBook Pro

Yes. The Mac mini can run the Gateway, and your MacBook Pro can connect as a node (companion device). Nodes don’t run the Gateway - they provide extra capabilities like screen/camera/canvas and system.run on that device.
Common pattern:
Gateway on the Mac mini (always‑on).
MacBook Pro runs the macOS app or a node host and pairs to the Gateway.
Use openclaw nodes status / openclaw nodes list to see it.
Docs: Nodes, Nodes CLI.