How to use ECHO to set a variable in batch - windows

Question

I've been wracking my brain trying to figure out a way to use the ECHO command to set the value of a variable in batch.
I'm aware that you can abuse the FOR command to set command output as a variable.
For example:
for /F "delims=" %%A in ('ipconfig ^| findstr /i IPv4') do (set TestVar=%%A)
However, I cannot figure out a way in which to use the ECHO command as the source command which "set" would use as input for the variable.
Does anybody know if there is a way in which to accomplish this?
Here is more info to help clarify my goal.
The purpose of doing this would be so that I can filter the results of a command via findstr and other commands to strip out the characters which I cannot use in the script. I'd be then assigning this stripped output to a variable.
I am creating a batch script with which to sync the contents of any USB drive plugged into a specific system with a source folder on the system. I am trying to make it "smart" in that it will automatically filter out any network drives, etc. Network drives are assigned via GPO, so I don't want to rely on manually updating a drive list pulled from a text file, since forgetting to update such a file could cause a network drive to be overwritten.
I am already able to accomplish this goal by echoing to a "temp.txt" file and then having the script pull from this temp.txt file.
The other catch is that I'm logging the results of each "sync." I do not want it to create false success logs, so I've compiled the script in such a way that a failed sync (failed robocopy) does not proceed to the logging command which is an echo to a text file (assuming that the failure is of a type that robocopy doesn't run at all, it would still log if robocopy ran).
Here's my script if it helps clarify things, as well as a copy of the one config file that I allow to be present.
SCRIPT:
REM This script relies on the "SyncConfig.txt" file to be present in the same directory as this script in order to run successfully.
REM The "SyncConfig.txt" file specifies which drives are eligible to have their contents synced with the Rockwell VM drive.
echo off
cls
color c
echo THIS SCRIPT WILL EFFECTIVELY WIPE ANY DRIVE THAT IS PRESENT
echo WHICH IS NOT SPECIFICALLY EXCLUDED IN THE "SyncConfig.txt"
echo FILE! Press any key to continue or click the "X" to cancel.
pause
color a
set SourceDrive=F:\
setlocal ENABLEDELAYEDEXPANSION
for /F "skip=6 tokens=*" %%A in (SyncConfig.txt) do (
echo %%A| findstr /i /v "Not Included" > temp.txt
for /F %%B in (temp.txt) do (
robocopy /MIR !SourceDrive! %%B:\
echo %Date% > %%B:\LastSynced.txt
for /F %%C in (temp.txt) do (
dir %%C:| findstr /i "Volume" | findstr /i /v "Serial" >> temp.txt
)
for /F "skip=1 tokens=6,7,8,9,10 delims= " %%C in (temp.txt) do (
echo ------------------- >> SyncLog.log
echo %DATE% %TIME% >> SyncLog.log
echo sync performed for: %%C %%D %%E %%F %%G >> SyncLog.log
)
)
)
del temp.txt
endlocal
"CONFIG FILE" - SyncConfig.txt:
Lines which include the text "Not Included" anywhere in the line will be ignored. This is being used |Not Included
to prevent specific drives (such as mapped network shares) from being overwritten by the sync script. |Not Included
|Not Included
|Not Included
DRIVES: |Not Included
----------- |Not Included
A
B
C Not Included
D Not Included
E Not Included
F Not Included
G
H
I
J
K
L Not Included
M
N
O Not Included
P
Q
R
S Not Included
T Not Included
U Not Included
V
W
X
Y
Z