Python 3 script that replaces every webp on your desktop with a PNG. Requires Google's dwebp decoder (https://developers.google.com/speed/webp/docs/dwebp)

webp_begone.py

# Webp-Begone
#
# Iterates over all the files ending in ".webp" on the Desktop and converts
# them to PNG files using the Google utiltiy dwebp
# Alteratively a different directory path can be specified at the cmdline

# Install dwebp and add it to your path
# https://developers.google.com/speed/webp/docs/dwebp 
# https://storage.googleapis.com/downloads.webmproject.org/releases/webp/index.html

import os
from sys import argv
from shutil import which

if which('dwebp') is None:
    print('The utility dwebp cannot be found.')
    print('Visit: https://developers.google.com/speed/webp/docs/dwebp')
    input("Press Enter to continue...")
    os.exit(-1)

dir_path = None
if len(argv) > 1:
    if os.path.exists(argv[1]) and os.path.isdir(argv[1]):
        dir_path = argv[1]
    else:
        print(f'ERROR: Not a valid directory')
        input("Press Enter to continue...")
        os.exit(-1)

if dir_path is None:
    if 'HOME' in os.environ:
        dir_path = os.environ['HOME']
    if 'HOMEPATH' in os.environ and 'HOMEDRIVE' in os.environ:
        dir_path = os.environ['HOMEDRIVE'] + os.environ['HOMEPATH']

if dir_path is not None:
    dir_path = os.path.join(dir_path, 'Desktop')
    if os.path.exists(dir_path):
        os.chdir(dir_path)
        for filename in os.listdir('.'):
            if os.path.isfile(filename):
                root,ext = os.path.splitext(filename)
                if ext == '.webp':
                    os.system(f'dwebp {filename:s} -o {root:s}.png')
                    os.system(f'del {filename:s}')