Not really familiar with PureBASIC, could a Linux version be possible without the user libraries?
Absolutely. The libraries are written in Purebsaic for Purebasic and are just a collection of standard PB functions image and sprite functions.
If you're familiar with SDL and Raylib then that would be the way to go for you and convert the code.
The chipmusic can be easily converted to a standard WAV, MP3, OGG etc too.