I looked up “lead testing” and my state, and was directed to their health department’s recommendations for both lead in homes and for child care center testing. They have links to several labs with kits that get mailed to you, typically you swab or take a sample, then mail it back to the lab. There are also in home test kits for lead on sites like Amazon that process immediately (have a color change when lead is present iirc), idk how accurate those are but could be at least a good starting point for some items.

It’s like gold, you bite it and see if it’s soft.