How fast would that battery die? Also the screens probably add substantial weight. This thing isn’t practical at all, but it is very flashy.

I haven’t seen it mentioned here but you can use Plexamp along with multi-scrobbler attached to a service like listenbrainz or last.fm. This will record what you listen to and help come up with personalized recommendations.

It seemed like it was under more active development, and it syncs with Tachiyomi, it seems to be a better implementation to me

For manga, I use Kavita and connect to it with Tachiyomi on Android. I organize these files by hand outside of any system. I prefer this because it synchronizes and works well.

For regular books, I have Readarr synced with Calibre, which I then have Calibre-Web connected to, which then exposes an endpoint for my devices using opds with apps like moonreader+ on Android or an e-ink device running koreader.

I prefer my regular book setup for the organization Calibre brings along with the flexibility of Calibre-Web.