Unable to run .NET 6 docker 'runtimeconfig.json was not found'

One thing that strikes me is that you copy the .csproj file into a /src/src directory which seems wrong. You're aleady in the working directory /src and then you copy the file into a src directory below that. Try changing these lines in your dockerfile

# copy all the layers' csproj files into respective folders
COPY ["VisualOrder.csproj", "src/"]

# run restore over API project - this pulls restore over the dependent projects as well
RUN dotnet restore "src/VisualOrder.csproj"

to this

# copy all the layers' csproj files into respective folders
COPY ["VisualOrder.csproj", "."]

# run restore over API project - this pulls restore over the dependent projects as well
RUN dotnet restore "VisualOrder.csproj"