“…On the other hand, the FDEs involving the most generalized fractional differential operator called Ψ-Hilfer fractional derivative [22] has attracted considerable attention from researchers. The basic analysis of various class of nonlinear Ψ-Hilfer FDEs relating to the existence and uniqueness of the solution, Ulam-Hyers stability, comparison theorems, extremal solution and comparison result concerning lower and upper solutions can be found in [23,24,25,26,27,28,29,30,31].…”