Hummm.... So you will travel with the desktop case, 3 monitors, 1 keyboard and 1 mouse. You know, there are laptop with full-size keyboard and 17+ inches screen.
Maybe I'll have to take another look at laptops. I haven't purchased a personal computer since I built my current one about 5 years ago. At that point, I got a lot more for my money building a small desktop than buying a full-featured laptop. Times change though...
If the small form factor is an important parameter you might want to look what Intel has to offer with their NUC family: https://www.intel.com/content/www/us/en/products/boards-kits/nuc/kits.html
Not sure when Dell didn't suck. Had problems already in the 90's. Considered portable usb / hdd? I'm with you on laptops. They get way too hot, noisy, impossible to extend, painful to work at and the hw always underperforms.
What, you're a "Dell hater"? Back when, Dell made the mistake of having proprietary mobos and PSUs. The market taught them a lesson and they backed off to use "industry standard" parts.... and that was like 15 years (or more) ago. I've used Dell workstations exclusively for the last 10+ years. Currently have 6 of them in my network. If they truly "sucked", I'd be using something else.
Absolutely not, not at all really. You may go for solution with integrated video from .... I would say Ryzen for now and not Intel i-series cause that way it's much cheaper anyway. It's more than enough setup which you mention here, you just need to be sure that it allows so many monitors and it could be some issue with that cause it's rare case.