Most Android devices these days have a software navigation bar. They're pretty customizable too. You can use apps like Substratum to even change your navigation bar icons to make them look like a Pixel. However, a lot of customizations also require root.
NavBar animations does exactly as the name implies. It gives your device custom animations when you tap a navigation button, and works without root access. It's a free app on the Google Play Store, and it works on any device with a software navigation bar. Upon opening the app, you'll be greeted with a short intro screen, telling you to toggle the activation switch, and then allows you to pick a button animation of your choice.
On some devices, like the Galaxy Note 8, it may warn you that it didn't detect a navigation bar, just tap "OK" and proceed.
Each of these categories on the main screen has multiple options to choose from. Once you have picked one that you like, it should take effect immediately. It also has an "autostart on boot" option so that you don't have to open the app each time your phone starts up to activate it.
It's hard to really show the effect with an image, but here's an example of one of the basic animations in the app:
You can also adjust animation settings by tapping the gear icon in the upper right-hand corner, allowing you to adjust such things as animation length, whether it is triggered by a single or double tap, and the option to add a colour overlay to the animation for added effect.
As far as OS compatibility is concerned, it should work on devices running Lollipop (5.x) and above.
You can grab NavBar Animations from the Play Store below:
What do you think of this app? Let us know in the comments section below!