We were able to apply the month picker using an override that we found on the following link:
https://github.com/mitchellsimoens/extjs-date-picker/blob/master/overrides/panel/Date.js
Basically the code on the link above is creating the month picker using a dataview and the override is applying the month picker created on the existing date component.
To apply that you need to create the Date.js override file on the override folder that is configured in you ExtJS application and also you will need to create the month picker component as you can find on src/ folder on the link above inside the app/ folder in your project.
In a new local project this override have worked without any changes on the code, but in our project we had an error with the toolCt variable that was undefined, so we changed the line 83:
const toolCt = this.toolCt;
to be like:
toolCt = this.query()[0];
We also had some issues with the position of the month picker when displayed on minimized screen, that we handled using the responsive configuration on ExtJS. Basically when the screen is smaller then the date picker height we are changing the date component to a mobile version.