Is ECC RAM overkill for a home lab?

Probably not. Random crashes from memory errors are vanishingly rare with modern DDR4/DDR5, even without ECC. ECC is expensive, requires server-grade hardware, and gives maybe 0.1% more uptime. Most home lab crashes are from bad power supplies, dodgy drives, overheating, or driver bugs. Save your money and invest in a good UPS and reliable storage instead.