I managed to get it working with a simple fix.
Create a dxvk.conf file in the directory the game is installed. Usually $HOME/.local/share/Steam/steamapps/common/Small Radios Big Televisions/dxvk.conf
Add the following lines:
dxgi.deferSurfaceCreation = True
d3d9.deferSurfaceCreation = True
The explanation of what this does is here and many other options: https://raw.githubusercontent.com/doitsujin/dxvk/master/dxvk.conf
EDIT: also I used Proton 6.3-6 and 6.15-GE-2 and both work
proton 6.3-6x1 2021-08
Compatibility Report
System Information
steam-390040.log
I confirm:
Symptoms
When the game starts the screen is black, the sound starts and the cursor changes shape when you roll it across the screen but there are no graphics shown at all.
Reproduction
Start the game

steam-390040.log
Workaround iCCP didn't work
In the first time I ran the LOG file it came back with the following warning
iCCP: known incorrect sRGB profile
with:
pngcrush -n -q $( find . -type f -name "*.png" )I could see that the png files in the game did have incorrect sRGB profiles
I fixed the files using the following from the directory
/Steam/steamapps/common/Small Radios Big Televisions/res/texturesmogrify $( find . -type f -name "*.png" )