dxvk and dxvk-nvapi can also manually be added to proton. I wrote a small tutorial for Lutris, for steam you can use this.
You can upgrade the version of DXVK used in Proton, without waiting on a new release. To do so you can just overwrite the existing DXVK files with the release download of DXVK 1.9.3. You can find your Proton install somewhere like this (depending on your Steam Library drives):
path-to-your/SteamLibrary/steamapps/common/Proton x.x/distWhere x.x is whatever Proton version installed you wish to give a new DXVK.
Inside there you will see "lib" and "lib64", for 32bit and 64bit. Inside each of those, there's a "wine" folder and inside there is a "dxvk" folder and that's where you replace the files with new versions. Do so at your own risk but it's usually harmless. If you mess anything up, one way to ensure it gets reinstalled cleanly is just to remove the "/dist" folder..