If you add external monitors, keyboard and mouse you just recreated non-mobile work environment that costs more money and has worse performance than workstation.
I'm not arguing against desktops for people who like them but this "I don't understand laptops" stuff (several posts, not just this one) is bizarre.
I have a desktop, and a laptop used as a thin client. The laptop can be inexpensive or have nice features (like a touchscreen), while the real power, storage, etc, is on the desktop.
This isn't even an argument, the decades of the laptops continued popularity say enough.
My desktop is just a host for several VMs. If I actually need to travel with one of those "computers", I just shut down the VM and copy it's image from my NAS to my laptop.
If you are still buying a laptop for your stated reason, then you haven't embraced virtualization as a developer.
Making a VM copy from a NAS every time I decided to step outside and work say on the back deck in a different environment with trees and some sun is anything but convenient.
There seems to be a perpetuation falsehood in these discussions that the only time you would need to use a laptop is when travelling a substantial distance from home, which can not be anymore further from the truth than is possible.
Lastly, laptops are not the sole domain of developers and you don’t need to ‘embrace virtualization’ simply because it exists.