I've heard this music on an another game boy homebrew... Also really great game :)
Thanks a lot
And yes, the music in a very cool public domain resource file produced by a member of the talented GB Studio community, so it's used in several games :).
It's titled "In The Town" and composed by krümel (crumb)#0723, under a public domain license (GB Studio Community Assets): https://github.com/DeerTears/GB-Studio-Community-Assets/tree/master/Music