After testing, there is no problem in creating parameters through the following code：

    GVariantBuilder options_builder;
    g_variant_builder_init(&options_builder, G_VARIANT_TYPE("a{sv}"));
    GVariant *args = g_variant_new("(oa{sv})", adv_path, &options_builder);

    g_print("args: %s\n", g_variant_print(args, FALSE));
    g_dbus_proxy_call(proxy,
                      "RegisterAdvertisement",
                      args,
                      G_DBUS_CALL_FLAGS_NONE,
                      -1,
                      NULL,
                      on_advertisement_registered,
                      NULL);