Unity is famously capable of running on nearly anything. Until recently I used to take my 2013 Macbook Air out with me so I could do some work without lugging a gaming PC. It's always felt pretty lightweight to me. The exception is creating a new project where it has to download or import a lot of packages (especially if you're using URP or HDRP)
But loading an existing project with a valid Library folder and working interactively in the editor should feel pretty snappy.
