This program allows you to run any glibc executable on a non-glibc system (such as musl) assuming you have a glibc root at /glibc with the necessary libraries.

glibc.c

#define _GNU_SOURCE

#include<stdio.h>
#include<sched.h>
#include<sys/mount.h>
#include<unistd.h>
#include<stdlib.h>

int main(int argc, char *argv[]) {
	setenv("LC_ALL", "C", 0);
        unshare(CLONE_NEWNS);
        mount("/glibc/usr", "/usr", NULL, MS_BIND, NULL);
        mount("/glibc/var/db/xbps", "/var/db/xbps", NULL, MS_BIND, NULL);

        setreuid(getuid(), getuid());
        setregid(getgid(), getgid());
        argv++;
        if(!argv[0]) {
                argv = "/bin/bash";
        }
        execvp(argv[0], argv);
        fprintf(stderr, "Failed to execute program");
        return 1;
}