In terms of used, most anything (outside of press type cameras) will do, and only because press cameras will typically lack the movements needed for architecture.
Flatbed cameras fold nicer and are typically lighter. Monorail cameras are bulkier and heavier but more flexible. Modular monorail cameras are nice and versatile and you can pack only what you need and set up the camera system to be what you need/use (like how arca has field standards as an option) but you will pay for that flexibility.
Rent or borrow one if you can to start with to get a feel for using LF and what does and doesn't work for you.
Personally I'd look at the cheap Intrepid offerings (low cost, popular, not as many rear movements, flatbed camera) or a stenopeika hyper basic camera (flatbed camera, 360EUR, modern as well, can take bag bellows).
Both of those are cheaper than I got my fancy LF kit for heavily used and would have worked for what I did, so I can't really fault them.
I think for architecture people usually like wide lenses (?) which means bag bellows, while personally, for landscape work I've done I never cared too much about the lens for LF and just used what I had access to.
A book on LF technique that covers movements and styles (landscape, portrait, architecture, etc) will be fairly invaluable too as technique matters a lot when working with LF.
Getting some practice loading a filmholder is good too because the feeling of loading up a stack then taking them into the light only to find one sheet of slide film is on top of the darkslide feels expensive.
But yeah-rent or borrow some gear, get some LF specific book for technique, check out some photographers who use(d) LF for landscape and architecture and check out the composition and try to figure out how they set up the shot. Take note of what you do and don't like about gear, get a friend with an LF setup to take you out shooting.
There are some good LF photographers on youtube too who do go into details that are very informative too. I personally like Mat Marrash and Markus Hofstatter, Mat especially goes into a fair bit of detail about setups for shots, techniques in the darkroom, etc.