There’s a docker that essentially sets up a web VNC for Calibre. I do this for file conversion, DRM removal (only books I buy), etc.
Then I use Calibre-web for the OPDS server and nice web UI.
You can have calibre auto import from a folder. Though be careful because it deletes them from that folder (you might want to do single direction sync into that folder).
And if you share the db with calibre-web or have some other sync method that works, you should be good to go.
… comics and manga, which is another aspect I’ve been noticing calibre does not do such a great job
Absolutely. Calibre is horrible with anything that is fixed format. I recently backed up my entire Kindle library with about 1k manga volumes, expecting to be able to convert from KFX to EPUB format as I have been doing for my regular books for 15+ years. Calibre failed awfully at this. The only thing it’s reasonably good at with comics, is converting to ZIP format. So I had to write a Python script to take the KFX -> ZIP outputs from Calibre and convert them into working EPUB files.