With unpatched musl, not really. In the do_tzset function in __tz.c, I think changing the
"if (!s || !*s) s = __gmt;" to simply "if (!s || !*s) s = "/etc/localtime";" should do it, though I wouldn't say for sure without testing.

If you simply don't want to have to deal with manually setting TZ to match the /etc/localtime definition everywhere, TZ=/etc/localtime should suffice.