There are several different types of night vision devices and qualities.
I have not tried many, but a generation 1+ device was a bit disappointing.
Although of quite high quality, the field is narrow and there is severe edge distortion.
Also the edge performance is poor.
The only good view I had was of an amazing blizzard.
Another device is a low light level CCD or CMOS detector device, such as made by Meade a few years ago.
Again, binoculars were better, although it was interesting.
They may be getting better as low light level security cameras become better and cheaper.
Another device is an integrating camera I think like a Mintron?
This integrated perhaps up to 128 frames over 2 seconds and gave quite a good view on an old 6inch portable T.V. or a T.V monitor.
But for a moving animal they may not be very useful.
A used generation 2+ device is a revelation. 165mm f/2 coated lens, acting like a 5x 82mm device.
The field is virtually distortion free and of good quality more or less to the edge.
It is a bit heavy and long and is best on a tripod but can be hand held.
For astronomy it performs as well as a 20 x 80 binocular as far as faint stars are concerned, but instead of a 3 or 3.5 degree field it has over 6 degrees field. So one sees many more stars than in a binocular.
However, the resolution is similar to a 5x binocular.
So M 42, The Orion nebula is bright but small.
Jupiter's moons are very bright but difficult to resolve.
One has to take care with all these devices not to use them in bright lights or into a car headlamp as the tubes can be destroyed. Daylight can destroy them. They usually have a tiny hole in a tight fitting cap for daytime testing. The Sun would destroy them, may be even if they have protective circuits.
So one has to check carefully and have a careful programme when using them.
In addition, the tubes have a limited lifetime depending on type, and degrade over time even without use.
The generation 2+ device is impressive.
The infra red beam has three settings. It is claimed up to 150 plus metre range, but the 2 AAs get quickly drained.
The gain control has an enormous range and even at maybe 30,000x the resolution is good.
The device was available for about 650 euros, but I think worth it. New they may be around 2,500 euros?
This is a vast subject. I am sure othere have much more experience with these devices.
For some countries there are restrictions on high end devices.
Hope that helps