I have 515W on top of the roof of my sprinter. I also have a custom-built 12VDC-direct mini-ITX system that I use in the van (160W TDP). Because I do native development, not web related stuff, that means compiling a lot. The computer uses more power than the refridgerator. The 515W is enough for about 7-8 months of the year at the range of latitudes spanned by the USA. It's not enough during winter even in sunny NM or AZ.
I guess I was being a bit "greedy" on the analysis, cuz I was thinking about an M1 Macbook Pro, or just laptops in general.
An M1 Mac Mini max power draw according to Google is ~40W. Google tells me a 24 inch monitor is 20-60W. Maybe I'm looking at the wrong numbers, but that looks like a 100W thing? Perhaps that's totally off base though, or not comparable numbers. But I have to imagine that a laptop (or laptop-based infra) is gonna be better for you (even if you need the power in theory).
I have a laptop also (Lenovo Y700). Because I need the compilation power, it basically uses about the same amount of power as my custom built system. The difference is that it has its own battery, which changes (a little) the way it interacts with the van's power system.
