Found the solution:
npx for installing.
npm install --global hardhat-shorthand
yarn global add hardhat-shorthand
Hardhat team mentions something similar in their Context paragraph (refer below):
Out of best practice, Hardhat projects use a local installation of the npm package hardhat to make sure everyone working on the project is using the same version. This is why you need to use npx or npm scripts to run Hardhat.
This approach has the downside of there being no way to provide autocomplete suggestions directly for the hardhat command, as well as making the CLI commands longer. These are the two issues that hh solves.