Is it permissible to plant fruit-bearing trees and plants and eat their fruits on a neglected desert land owned by the government (public land for Muslims) in front of the house, knowing that we currently plant non-fruit-bearing ornamental plants there to beautify the street?

It is permissible to cultivate barren land and benefit from its produce, provided the government does not prohibit its reclamation, because it belongs to whoever reclaims it, and the majority of scholars hold that government permission is not required. However, if the government has taken possession of the land or prohibited its reclamation, then it is not permissible to cultivate it without the government's permission.