import os
from os import walk, rename, system
from os.path import join, splitext

origpath = 'C:/Users/florian/AppData/Local/Packages/Microsoft.Windows.ContentDeliveryManager_cw5n1h2txyewy/LocalState/Assets'
mypath = 'C:/Users/florian/Desktop/Assets'
if not os.path.exists(mypath):
    os.makedirs(mypath)
system('cp ' + origpath + '/* ' + mypath + '/')
for (dirpath, dirnames, filenames) in walk(mypath):
    for f in filenames:
        src = join(dirpath, f)
        dst = splitext(src)[0] + '.png'
        rename(src, dst)
        print(src, dst)
    break