Advice for Starting My Homelab Journey with Existing Hardware

Hey everyone! I'm a new IT student looking to dive into my homelab journey. My main goal is to learn and experiment while setting up a private cloud to minimize reliance on third-party services. I'd appreciate your input on how to start with the hardware I already have, as I'm not planning to buy anything new right now.

Here's what I'm working with:
- **Laptop:** It's my personal daily driver, so I can't use it as a permanent server.
- **Home desktop:** It's an i3 9th gen with 16GB RAM, an NVIDIA 1060Ti, and a 256GB SSD. I want to keep this for family use (including occasional gaming) but also use it for LAN services. I'm considering switching to a user-friendly Linux distro that still maintains a GUI while allowing for terminal/server capabilities.
- **Old PC:** A very old Intel Pentium with a ~128GB SSD. I'm unsure about repurposing it—open to suggestions.
- **External SSD:** I have a 256GB external SSD for storage and backup experiments.
- **Network gear:** Just a basic consumer ISP router.

A bit about my background: I have basic networking, development, and sysadmin knowledge and want to learn more by doing. I'm looking for ways to make the most of what I already have.

**Here are my main questions:**
1. What beginner projects would you suggest?
2. Any distros you'd recommend for the desktop that balance usability (for family gaming) and server capabilities?
3. Is the old Pentium worth revamping for lightweight tasks, or should I primarily focus on the desktop?

I'm excited to learn, so any beginner-friendly advice or project ideas would be really appreciated. Thanks in advance!