Function xmtp_device_sync_create_archive 

pub unsafe extern "C" fn xmtp_device_sync_create_archive(
    client: *const XmtpFfiClient,
    path: *const c_char,
    opts: *const XmtpFfiArchiveOptions,
    key: *const u8,
    key_len: i32,
) -> i32

Export an archive to a local file. key must be at least 32 bytes (encryption key).