8 hours of offline Spotify possible?

Hey all, I have a job that has me in a secure area, so I'm not allowed to bring phones in. But I'm allowed to bring in a smartwatch for offline listening. Recently got the Galaxy Watch 6 open-box for $80, and currently offline listening on Spotify is terrible. I often lose around 15-20% per hour while listening to medium-quality downloaded music, with battery saver on. Can this watch really not last a whole workday with this setup? Are there any similarly priced watches or portable audio players that would last longer? I'm only using my watch for Spotify.