You can find those kind of sticker packs on ebay and other shopping sites.(Goes for around 2 - 10 US bucks) You can also custom print your own ones (Usually hella ton cheaper)
Some Chinese manufactures actually gave the ability to switch around the order of the buttons on the nav bar. I don't think pixels have a option like that, gesture navigation might be the only option that will be comfortable ig
I tried it out on my laptop that's running Fedora and so far it's great. it's a shame that the development of it has ended.
I'm thinking of using Outertune when i get myself a pixel and install GrapheneOS on it.