Even just making sure that it passes some common automated testing tools like the Wave Toolbar from WebAIM would be great. From Tenon you can see about 82 that are reported just for the front page https://tenon.io/testNow.php?url=https://react.lightningdesignsystem.com/

Lots of folks are moving to aXe-core so that’s also an option. It doesn’t catch everything, but anyone making claims about accessibility should have a demo that at least covers the low hanging fruit.