In my experience, the developer experience for juniors is too much. Yarn + Lerna is just too much of a learning curve. However, having one repo and on CICD pipeline is convenient. But we've decided to divest from them. Your situation may not match mine, and that's okay.
Lerna is only needed if you're publishing multiple packages from the monorepo. If you're consuming your packages only within the monorepo for your various services, Yarn Workspaces is generally all that's needed.
