I think it’s difficult to say. It makes some intuitive sense that a phone that can more easily come apart nondestructively can better survive the type of treatment you describe - but then, maybe a glued-together, solid, unfair phone would hold up better by not coming apart at all. I owned a Sony Xperia Z1 for seven years, and it took many a tumble without ever falling apart or breaking. My FP2, on the other hand, has needed a bit of a talking-to with a screwdriver every now and again, fall or no fall.
So what that means for the FP3, who knows. In a sense it’s more modular than the FP2, containing more separate modules, but it is more securely put together.
Purely anecdotally, from having used both phones, I’d say the FP3 will hold together better. It feels stronger, less creaky and bendy than my beloved FP2.
Any volunteers for driving over their FP3, for science?