Yep this is actually where I started (not sure it qualifies as a “borescope” but what I initially put in the dust shoe was such a very small camera), but then I looked for a model that would be higher resolution AND be able to support higher framerates AND would not require some silly custom Android app over wifi, and could not find a satisfactory model (but they probably exist!)
I do miss that very small form factor that was perfect for dust shoe integration.