Kanban Board Subgroup Customization

Hi fellow developers,

Currently, we are looking to customize the Kanban Board to have something like a subgroup feature. Below is the Subgroup feature from Notion:

From the image, the top (Happy, Neutral, Unhappy) is the group like in Frappe, in each column, there are different sections (High, Medium, Low) to indicate the subgroups.

We have run through the forum and Google but did not see a viable solution.
A few solutions we found:

  • Directly change the source code:
    • We don’t want to do this because this will break on the next ERPNext/Frappe update.
    • and we are hosting in Frappe Cloud so changing the standard source code will not work.
    • even if we submit a pull request, it could take some time to include this feature in the standard.
  • Create a custom page and build our own Kanban:
    • This might be a solution but this could take some effort so we will look into other possible solutions first, and building a custom page is the last choice.

Other thoughts are to override the Kanban Board template file and the controller file which we do not find a way to do so. I know we can use hooks to override doctype controller/script, but is there a way to override other files (template, python, js) which does not belong to a doctype/whitelisted?

Any thought on this? Any suggestion is appreciated. Thanks in advance.