I want this device!

> lasts a full day on a charge

The iPod Classic could do 36 hours of playback so I wonder why this can only manage 24 hours.

> 2200-mAh battery with a standard, 3-pin JST connector

For years I have wanted a MP3 player with a 18600 battery. If the developers are reading this, consider a version with a 18600, even if the form factor is not as ergonomic.

> Firmware supports MP3, FLAC, Opus, and Vorbis codecs

No audiobook (m4b, directory of MP3s) support yet. This would be a nice feature to have.