As with
yo @microsoft/sharepoint --package-manager pnpm
it would be great to get the commands with the right package manager. It's not hard to edit the commands manually, but there may be some syntactical differences over time.

The current options are:

--package-manager | The package manager for the solution. Options are: "npm", "pnpm", or "yarn". Default: npm

(See: https://docs.microsoft.com/en-us/sharepoint/dev/spfx/toolchain/scaffolding-projects-using-yeoman-sharepoint-generator)