Frontera by Julio Anta and Jacoby Salcedo

As long as he remembers to stay smart and keep his eyes open, Mateo knows that he can survive the trek across the Sonoran Desert that will take him from Mexico to the United States. That is, until he’s caught by the Border Patrol only moments after sneaking across the fence in the dead of night.
Escaping their clutches comes at a price and, lost in the desert without a guide or water, Mateo is ill-prepared for the unforgiving heat that is sure to arrive come sunrise. With the odds stacked against him, his one chance at survival may be putting his trust in something, or rather someone, that he isn’t even sure exists.
If you’d asked him if ghosts were real before he found himself face-to-face with one, Mateo wouldn’t have even considered it. But now, confronted with the nearly undeniable presence of Guillermo, he’s having second thoughts. Having spent his afterlife guiding migrants to safety, Guillermo knows things about the Sonoran Desert far beyond what could be explained by a mere hallucination. But even as Mateo forms an uneasy partnership with Guillermo, survival is still uncertain.
The Sonoran Desert, with its hostile temperatures and inhabitants, is teeming with danger as the Border Patrol and rogue militias prowl its deadly terrain. As his journey stretches on, Mateo will have to decide exactly what and who he’s willing to sacrifice to find home.