NPS Browser for NoPayStation but you'll need to use a PC.
I don't think there's a homebrew app for PSP that lets you download official PSP games like freeshop.
as ov3rkill already said, there is NoPaystation for: vita, psp, psx, ps3, psm, pc-engine and neogeo games/dlc. but you need a pc to use the "nps browser" and it wasn't ported to psp(yet)