In microservices Lerna monorepo there is a need to publish to npm?

I’m new to monorepo projects/concepts.

I always hear that in Lerna we should publish our packages to NPM. Is it a must?

It makes sense to publish to NPM if we want to share a specific package with other projects.

If I want to build a monorepo of microservices, there is no need to publish to NPM.

Am I right?

Thanks.