We divided an ancient Snake (a.k.a. Mother-In-Law’s Tongue) Plant and discovered the pot had no drainage hole, which is not to be tolerated.
It turns out that an ordinary carbide glass drill works just fine on glazed clay pots. Use a low RPM and very slow feed, flood the scene with water, and drill from the other side after the point breaks through.
The glaze inside the pot already had a flaw that let the water into the clay, from whence it seeped out through the unglazed lower rim. I suppose saturating the clay can’t possibly be good, but I’ve done this to many glazed pots over the years and none of them have ever complained, so it’s all good.