Many of the MMwave sensors intentionally don’t look like cameras. That’s also part of the point. They are used in a lot of situations where privacy is required, like hospitals. Take a look at the link and you’ll see some of the options currently available, but of course it’s up to you. Choice is good. 
Best mmWave Sensor to Use with ST? (human presence sensor/occupancy sensor)
btw, not only can the MMwave sensors detect through glass, they can detect through many opaque materials, even a thin plaster wall or a box cover. So you can hide them completely if you choose to. (I have one at my house sitting on a shelf inside a basket, and it works fine.) I’m not sure if that’s more or less creepy, though. 