There are a few ways to pass the list of files returned by the find command to the cat command, though technically not all use piping, and none actually pipe directly to cat.
unix - How to pipe list of files returned by find command to cat to ...
How to get the last line of a file using cat command
cat is a synonym for the Get-Content command, which simply reads the content of document referenced by the passed parameter and outputs to the standard output the contents of it.
If using an external utility is acceptable I'd prefer busybox for Windows which is a single ~600 kB exe incorporating ~30 Unix utilities. The only difference is that one should use "busybox cat" command instead of simple "cat"
stop using cat when you don't need to. awk '....' raw_data.txt | sed ... Also, what is your intent with cmd = "cat ... Just to initialize a variable with the string literal cat raw_... ? OR to assign the output of the that command chain to the variable cmd? I'll be surprized if others can show you a way to achieve a common syntax between Windows and Unix, unless you're using a Unix on Windows ...
The cat <<EOF syntax is very useful when working with multi-line text in Bash, eg. when assigning multi-line string to a shell variable, file or a pipe. Examples of cat <<EOF syntax usage in Bash:
linux - How does "cat << EOF" work in bash? - Stack Overflow