If you're unfamiliar with iOS shortcuts, they are mini applications anyone can build that allow you to automate various tasks. Learn more here: https://support.apple.com/en-gb/guide/shortcuts/welcome/ios

If you install the Shortcut linked above, it will work without installing any additional apps.

You can even manually run the Shortcut by adding it as a widget to your home screen and it'll prompt you to select an image from your photo gallery to upload.