Mexicans aren’t a bunch of snowflakes. Their feelings would be fine. As for wildlife, funding a wall is different than building it in accordance with environmental and other regulations.
My biggest objection was always the waste of taxpayer dollars so I support crowdfunded wall.
you are wrong on both counts. i'm not saying they are "snowflakes". i'm saying it would foster anti-americanism, which would have long-term negative consequences for both nations. as far as wildlife goes, i don't believe there is a way to build a barrier that is non-permeable to humans but permeable to large mammals. being able to cross the border is important to maintaining viable populations of several rare and declining species currently (e.g. mexican black bear, sonoran pronghorn) and would prevent or make much less likely the possible recovery of others (e.g. mexican wolves, jaguars) in parts of their range.
I don't claim to know how your typical Mexican leader or citizen thinks, but my guess is any trade talks or dismantling of NAFTA is much more critical to any anti-american sentiment compared to constructing a wall. I don't expect my neighbors to take it personally if I build a privacy fence (or even a moat) on my property.
On the second, I don't claim to know what damage would or would not be caused by added development, but I suspect you could mitigate at least some of it with parts that are permeable (to both animals and man) that are patrolled by guards / monitored by cameras. Again, I think it is a complete waste of money. I just don't think the down sides are really that problematic if it gets built without taxpayer dollars.