Should I install on a second laptop or just add a node

If you only need local tools (screen/camera/exec) on the second laptop, add it as a node. That keeps a single Gateway and avoids duplicated config. Local node tools are currently macOS-only, but we plan to extend them to other OSes.
Install a second Gateway only when you need hard isolation or two fully separate bots.
Docs: Nodes, Nodes CLI, Multiple gateways.