Before the recent waves of Venezuelan immigrants, most discussions I've seen about the topic was related to preserving the jungle, but some people for sure made snarky comments about keeping colombian gangsters out.
Nowadays, most of the attention are definitely on the Venezuelan immigrants that come to Panama without much money or much of a plan.
But if the government signed a deal to construct a highway, I predict it would be mostly environmentalists protesting in the street than xenophobes.
For sure, a garmin gps would help. They're not 100% though. I have a property in the mountains with jungle and there were steep drops that did not show up on my topographic map. I imagine someone could easily die if they didn't pay attention.
Also, slipping and falling is a serious risk during the wet season, even on well known paths.
The Darien Gap still has foreigners (including wealthy tourists) going there with the crazy idea they can hike through it. The trash being left behind in just the past couple years is just heartbreaking.
Mountainous jungles in Panama are extremely easy to get lost in the overgrown vegetation. Tourists have died in hiking trails in Boquete, Veraguas or Cerro Azul by only going a few hundred meters off path.
Also, most Panamanians are against the idea of building a road between Darien and Colombia since most of us want to preserve as much jungle as we still can.
There is currently massive protests against the mining operation in Donoso by the Canadian company First Quantum Minerals (FQM). I imagine there would be similar blockades against foreign companies trying to build a road in the darien gap.