gpg from gnupg.tcz in PiCore 16 (aarch64) fails to start without bzip2-lib.tcz and sqlite3.tcz loaded:
$ ldd `which gpg`
linux-vdso.so.1 (0x0000007fb14a5000)
libz.so.1 => /usr/lib/libz.so.1 (0x0000007fb1420000)
libbz2.so.1.0 => not found
libsqlite3.so.0 => not found
libgcrypt.so.20 => /usr/local/lib/libgcrypt.so.20 (0x0000007fb1350000)
libgpg-error.so.0 => /usr/local/lib/libgpg-error.so.0 (0x0000007fb1310000)
libreadline.so.8 => /usr/local/lib/libreadline.so.8 (0x0000007fb12a0000)
libncursesw.so.6 => /usr/local/lib/libncursesw.so.6 (0x0000007fb1220000)
libassuan.so.0 => /usr/local/lib/libassuan.so.0 (0x0000007fb11f0000)
libc.so.6 => /lib/libc.so.6 (0x0000007fb1070000)
/lib/ld-linux-aarch64.so.1 (0x0000007fb1460000)
I suggest that bzip2-lib.tcz and sqlite3.tcz are added to gnupg.tcz.dep for PiCore 16.