Always cool to see old boards learn new tricks. I thought for a second "wait, my Thinkpad X230 from 2012 can boot from M.2" but then I remembered it has mSATA, not M.2.
Sounds like a nice setup though. I too have an old laptop that's been running 24/7 for years. Kind of the perfect small server - low noise/heat/power and has a built-in console.