Sharing a specific version of a specific dependency within a monorepo: Simply add the shared dependency to the "root" package.json:

/package.json 👈 Add your shared dependency here 👈
/packages/shared/package.json
/packages/frontend/package.json
/packages/backend/package.json

This works across package managers, npm, yarn, pnpm, etc.

More details here: How can make all packages in a monorepo share the same verison of a dependency?