This is the thing that is most frustrating to me about MacOS—keyboard support is clearly a second class citizen.
It seems like you're supposed to use the trackpad for everything, but when I'm docked I want to use an external keyboard and mouse. The only mouse that supports the trackpad controls that Mac assumes are available is the magic mouse, which my company helpfully provided, but the ergonomics on that mouse are terrible. It's this tiny little flat slab that offers nothing in the way of support.
If I could figure out how to control everything with the keyboard I'd swap that mouse out for an ergonomic one, but virtual workspace management with pure keyboard seems to be impossible even with Rectangle installed.