Because of the small size of the hidden camera, or camouflage, resulting in poor heat dissipation, video quality and night vision quality than other cameras, and will be more problems.
If you do not particularly need a hidden mini-camera, then I do not recommend you to buy.
If you confirm the need to buy, then I recommend the following hidden cameras.
A10 Plus Hidden Camera – AREBI
LUOHE Hidden Camera
Disguised as a charger
MEE007 Hidden Camera – DIVINEEAGLE
1. Disguised as a charger
GooSpy Spy Camera
Can be DIY