Borescope?

I didn't spend $100-200 on mine. If you want to go cheap and go with one that connect to a phone rather than have dedicated screen, you can get great resolution and clear images without spending much.

I think I paid less than $30 on mine. See review below. I think the particular model I got maybe discontinued, but similar one linked from the review article below is a newer models on Amazon.

Depstech 86T-5M review | Digital Camera World

Used for, car, drain pipe, rat nest, and a few other occasions. Side view attachment made it great for seeing surrounding areas. But I would pay a bit more and get a dual lens one now they are readily available like this one.
Dual-lens WiFi HD Endoscope Camera - DEPSTECH WF028
Look for the same one in Amazon for sale for $44 now.

 

I was so pleased with one Depstech that I bought another.

One thing that didn't please me was the need for a dedicated app. The hardware presents itself as a standard UVC video source, and if I plug it into a Linux desktop, it gets claimed as a video4linux device and is available to select as an input in any app I already have around that handles video. But that doesn't happen on Android, and Depstech points you to a special app of their own to download in order to use it.

More recently, I did discover an open-source Android app called UVC_Camera, which is able to work with the Depstech (and, presumably, other UVC video devices). The app is still quite rough: it can query the camera for the available settings, and you kind of have to choose among those until you start seeing pictures. A colleague of mine called it true plug and play: you plug it in, then you play with it until it works.

 

Use case?
I haven't found a good reason to get one, yet........