Samsung brought on-screen navigation keys this year to the Galaxy S8, but they still aren't the same as what every other company uses. Samsung did at least make it easy for users to swap the back and recents keys, but for those that wanted a bit more of a Pixel navigation key look on their Galaxy S8, well the folks at XDA have you covered. A users has created an APK that you can install and change up those softkeys. However it's more of a workaround instead of straight up getting rid of those softkeys. You see, it's an overlay. So you still have Samsung's softkeys there, but now you have the Pixel ones on top of them. And as you'd expect, there are some bugs.
None of the bugs are showstopping, but the home button will briefly change back to the Samsung home button when you press it. It's not a huge deal but it does happen every time you press it. It's likely something that they'll be working on and fixing - likely pushing out a new APK soon. There are a few other small bugs with this APK, which are outlined on the XDA forum thread at the link below. It's a good way to change up those softkeys and get your Galaxy S8 to be even more stock Android (especially with the number of "material" themes already available for Samsung devices).
The APK does not require any type of rooting to your Galaxy S8 or Galaxy S8 Plus, which is definitely a good thing. And the buttons do actually look really good on these smartphones. It's a really basic APK, and will likely add a few more features (perhaps AOSP buttons as well, seeing as those are different from the Pixel buttons right now). But for those that were wanting to get those Pixel-esque softkeys onto their Galaxy S8 or Galaxy S8 Plus, you can head to the source link below and download the APK. Simply sideload it like you would any other APK or app onto your Galaxy S8 and you'll be all set. It's probably the easiest mod ever to set up.