While Windows uses the Python Launcher (`py -0`) to switch between versions, on GNU/Linux, tools like `pyenv` offer similar flexibility, although you could even run different versions of Python in virtual environments. Here's how you can manage multiple Python versions on Debian-based servers:

### **Method 1: Using `pyenv` (Recommended)**

`pyenv` is a tool specifically designed to manage multiple Python versions on Unix-based systems like GNU/Linux. It allows you to easily switch between different versions without breaking nor affecting the system's default Python installation.

#### **Steps to install and use `pyenv`:**

1. **Install dependencies for `pyenv`**:
   ```bash
   sudo apt update
   sudo apt install -y make build-essential libssl-dev zlib1g-dev \
   libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm \
   libncurses5-dev libncursesw5-dev xz-utils tk-dev \
   libffi-dev liblzma-dev python3-openssl git
   ```

2. **Install `pyenv`**:
   ```bash
   curl https://pyenv.run | bash
   ```

3. **Update your shell configuration to include `pyenv` in your PATH.** Add the following lines to `~/.bashrc` or `~/.bash_profile`:
   ```bash
   export PATH="$HOME/.pyenv/bin:$PATH"
   eval "$(pyenv init --path)"
   eval "$(pyenv init -)"
   eval "$(pyenv virtualenv-init -)"
   ```

4. **Restart your shell**:
   ```bash
   exec $SHELL
   ```

5. **Install different versions of Python using `pyenv`**:
   ```bash
   pyenv install 3.9.19
   pyenv install 3.12.5
   ```

6. **Set the global or local Python version**:
   - To set the global default version:
     ```bash
     pyenv global 3.12.5
     ```
   - To set a local version (specific to a directory/project):
     ```bash
     pyenv local 3.9.19  # Generates a '.python-version' file
     ```

7. **Run a specific version of Python**:
   ```bash
   pyenv shell 3.9.19  # Temporarily use Python 3.9.19
   ```

8. **Run a script with Python 3.9.19 without changing the global or local version**:
   ```bash
   pyenv shell 3.9.19 && python your_script.py
   ```

9.  **Show all available versions.** Similar to `py -0` on Windows:
   ```bash
   pyenv versions
   ```

### **Method 2: Manual Installation and Managing with Virtual Environments**

Alternatively, you can manually install different Python versions from source and use virtual environments to manage them.

#### **Steps:**

1. **Download and compile the desired Python version**:
   ```bash
   wget https://www.python.org/ftp/python/3.9.19/Python-3.9.19.tgz
   tar -xzf Python-3.9.19.tgz
   cd Python-3.9.19
   ./configure --enable-optimizations
   make -j $(nproc)
   sudo make altinstall
   ```

2. **Create a virtual environment with the specific version**:
   ```bash
   python3.9 -m venv ~/myenv39
   source ~/myenv39/bin/activate
   ```

3. **To switch between Python versions, activate the relevant virtual environment**.

### **Conclusion**

Using `pyenv` is the most convenient method as it simplifies managing multiple Python versions, switching between them, and even creating virtual environments tailored to specific versions. Method 2 is really just included for contrast of thought.