Not sure if the Wayback Machine supports API-based on-demand archival, but they do partner with firms like Cloudflare to auto archive websites: https://archive.is/O9SAO
There's availability API but it won't tell us if the archived webpage does indeed display content (say, if it was behind a paywall or cookie banner): https://archive.org/help/wayback_api.php
> There's availability API but it won't tell us if the archived webpage does indeed display content (say, if it was behind a paywall or cookie banner
Right - that's the problem. It takes a human to tell if the archive link is worth anything.
I do want to do something better with this someday (someyear?) - most likely a way for community members to submit and vet archive links, and then (if so) an "archive" button in the detail bar to point to it.