[Feature Request] Sync Progress with KOReader

[raygan]

Is your feature request related to a problem? Please describe.
I see Kobo progress sync and Hardcover.app are being worked on. I think it would also be great to sync reading progress with other ereaders running KOReader. This would include jailbroken Kindles and ereaders from Pocketbook etc, as well as Android devices.

Describe the solution you'd like
Calibre-web-automated could act as a KOReader sync server, adapting or including the project here: https://github.com/koreader/koreader-sync-server

For books in the Calibre library, progress could be displayed on the book page and synced to Hardcover.app.

Additional context

Komga, a comics and manga focused self-hosted library app, added a similar integration recently.

The KOReader software can currently only be configured with a single syncing server. This means that a project like Calibre-web-automated would either need to handle syncing of progress data for any book, not just those found in its database, or it would need to proxy those sync operations to a different sync server. Komga currently does neither, but has suggested it may add the option to proxy syncs for books it doesn't recognize in the future.

[BredMan0]

This would be great to have.