Hi Vijay,
The pyRevit guides on notion will have all the information you need to create the extension and buttons: https://www.notion.so/Create-Your-First-Command-2509b43e28bd498fba937f5c1be7f485
This explains the anatomy of an extension folder; subfolders (buttons), bundles (UI sorting and command info stored in a yaml file) and scripts in detail.
Once the button is visible on your toolbar you will be able assign it as you would any other keyboard shortcut in Revit (shortcut KS).