Run without root. Install macOS 10.14+ dynamic HEIC wallpapers on Linux (in GNOME). You will need `exiftool` and `heif-convert` to be available in your PATH. All created wallpaper and config files' names are printed out. At the moment this script lacks support for sun-based wallpapers. Some H24 wallpapers might also be parsed incorrectly.

heic-to-gnome.py

import plistlib
import sys
import os
import json
import base64
from pathlib import Path

name = ".".join(sys.argv[1].split(".")[:-1]).split("/")[-1]

if sys.argv[1].split(".")[-1] != "heic":
  print("File is not HEIC")

images_directory = os.environ["HOME"] + "/.local/share/backgrounds/" + name
config_path = os.environ["HOME"] + "/.local/share/gnome-background-properties/heic-desktop-backgrounds-" + name + ".xml"

if Path(images_directory).exists():
  print("There already is a folder for this image in ~/.local/share/backgrounds")
  exit(1)

if Path(config_path).exists():
  print("This background is already registered in GNOME")
  exit(1)

exif = json.loads(os.popen("exiftool -j \"" + sys.argv[1] + "\"").read())[0]

if not "H24" in exif:
  if "Solar" in exif:
    print("Solar based wallpapers cannot be processed yet") # TODO: add support for those
  else:
    print("EXIF meta for dynamic wallpaper not found")
  exit(1)

try:
  data = plistlib.loads(base64.decodebytes(exif["H24"].encode('utf-8')))
except plistlib.InvalidFileException:
  print("Not supported image format")
  exit(1)

if not "ti" in data:
  print("Not supported image format")
  exit(1)

print("Created: " + images_directory)
os.makedirs(images_directory)

if not Path(os.environ["HOME"] + "/.local/share/gnome-background-properties/").exists():
  print("Created: " + os.environ["HOME"] + "/.local/share/gnome-background-properties/")
  os.makedirs(os.environ["HOME"] + "/.local/share/gnome-background-properties/")

ti = data["ti"]

print("Created " + images_directory + "/" + name + ".xml")
meta = open(images_directory + "/" + name + ".xml", "w")
meta.write("<background>\n")
meta.write("  <starttime>\n")
meta.write("    <year>2021</year>\n")
meta.write("    <month>1</month>\n")
meta.write("    <day>1</day>\n")
meta.write("    <hour>0</hour>\n")
meta.write("    <minute>0</minute>\n")
meta.write("    <second>0</second>\n")
meta.write("  </starttime>\n")

# TODO: add transitions
for i in range(len(ti)):
  t = ti[i]["t"]*86400
  if i != 0:
    t -= ti[i - 1]["t"]*86400 # TODO: better length handling
  pic = ti[i]["i"] + 1
  meta.write("  <static>\n")
  meta.write("    <file>" + images_directory + "/" + name + "-" + str(pic) + ".jpg</file>\n")
  meta.write("    <duration>" + str(t) + "</duration>\n")
  meta.write("  </static>\n")

meta.write("</background>\n")
meta.close()

os.system("heif-convert -q 50 \"" + sys.argv[1] + "\" \"" + images_directory + "/" + name + ".jpg\"")

print("Created: " + config_path)
list = open(config_path, "w")
list.write('''<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE wallpapers SYSTEM "gnome-wp-list.dtd">
<wallpapers>
    <wallpaper deleted="false">
        <name>''' + name + '''</name>
        <filename>''' + images_directory + "/" + name + ".xml" + '''</filename>
        <options>stretched</options>
    </wallpaper>
</wallpapers>
''')
list.close()