The name of the board which has its pinout mirrored is actually D1 MINI, not MINI D1.

Author: dok-net

boards.txt

@@ -3648,7 +3648,7 @@ ttgo-t-watch.menu.DebugLevel.verbose.build.code_debug=5
 
 ##############################################################
 
-mini32.name=WEMOS MINI D1 ESP32
+mini32.name=WEMOS D1 MINI ESP32
 
 mini32.upload.tool=esptool_py
 mini32.upload.maximum_size=1310720

package/package_esp32_index.template.json

@@ -29,7 +29,7 @@
               "name": "WEMOS LoLin32"
             },
             {
-              "name": "WEMOS MINI D1 ESP32"
+              "name": "WEMOS D1 MINI ESP32"
             }
           ],
           "toolsDependencies": [