how to share dev-dependencies between Python projects within the same monorepo?

I have two monorepos like this:

.
├── monorepo1/
│   ├── apps/
│   │   ├── app1/
│   │   └── app2/
│   └── libs/
│       ├── lib1/
│       └── lib2/
└── monorepo2/
    ├── apps/
    │   ├── app3/
    │   └── app4/
    └── libs/
        ├── lib3/
        └── lib4/

Each monorepo contains apps and libs which contains python packages.

I want to share dev-dependencies for the same monorepo, but I did not find a way to do that. I'm using Poetry to manage Python package dependencies.

• Using poetry add -D will only install dev-dependencies in that Python package (e.g.e app1).
• Installing packages as global packages will influence other monorepos.

How could I install dev-dependencies once for all in a monorepo1?

Additionally, I'm using VSCode, and setting settings.json for each python project to use its own python env. For example:

// monorepo1/apps/app1/.vscode/settings.json
{
  "python.pythonPath": ".venv/bin/python",
}

How could I make it possible to find monorepo's dev-dependencies (e.g. pytest / pylint / black / ipykernel...) without installing those dev-dependencies for each python project within the same monorepo?