I have tried most answers here along with others on SO, nothing worked for me. The only thing that finally worked was:

1. Force quitting all Docker related processes
2. Installing Docker Desktop from the command line, instead of opening up the .dmg file from the Downloads folder. The CL instructions can be found here: docker: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?.

I'm not sure why step 2 worked instead of the regular download/install process, but I'm hoping it can help someone else.