Sandisk used to offer basic old-school mp3 players but looks like they shut them down. Can still find used on Amazon/ebay.

iOS has KMPlayer which was good the last time I used it: https://apps.apple.com/us/app/kmplayer/id835776444

Also Plexamp if you want to use Plex.

Walmart has a big selection of mp3 players: https://www.walmart.com/search?q=mp3%20player&typeahead=mp3%... However, i was not able to find good enough one that I would recommend. You can try searching yourself.

I personally use Plexamp and Musi.