This is a JS script intended to be run on the IOS Scriptable app. This script gets you the latest wallpapers from various wallpaper subreddits, the output can be used by the IOS Shorcuts app as a file.
How to use on iPhone
Download the Scriptable app
Download the JS file
Go to the JS file in the files app
Press the share button and share to Scriptable
Press Add to My Scripts
Go to the Shortcuts app
Create a new shortcut
Search for the action Run Script and place it in the shortcut
Change the script you run to the one you just downloaded
Search File and put the output through the File action
Search Set Wallpaper and select the wallpaper you want to change
Click the arrow and turn off Show Preview
How to add/change the subreddits the wallpapers are from
Copy the link of the subreddit you wish to add
At the very top of the JS script you will see the array RedditUrls
Add the reddit URL between "" and add a comma at the end (if you want to add more)
Then add /new.json?limit=5 to the end of the reddit URL