While this does not address your question directly, and to save offline is often best
& fastest; your Mac can save files images text, using Finder. As article suggests:
Use the Finder to share files between your Mac and your iPhone, iPad, iPod touch - Apple Support
//support.apple.com/en-us/HT210598
Or, with older computer: IF you're using macOS Mojave or earlier, or a Windows PC:
use iTunes to share files between your computer and your iOS or iPadOS device.
Learn how to set up iCloud Photos on all of your devices - Apple Support
(Hand off, AirDrop, iCloud Drive? external drive to wireless local base; etc.?)
Sync photos between your Mac and iPhone, iPad, or iPod touch - Apple Support
How to use Shared Albums in Photos on your iPhone, iPad, and Mac - Apple Support
support.apple.com/en-us/HT202786
..Of course most-to-none of those Online items works for me here in AK..
And I feel your pain, most devices now need fast + consistent internet.
Sorry to not find correct exact results, between bookmarks & searches.