This. Big Macrium fan here. There is no practical way to split PROGRAMS that are installed across drives. Windows just writes stuff all over the place besides the programs folder, the registry too. So programs either must be moved with the OS. You can remove them after you get the new drive up and running, then reinstall them with a custom install and specify to install on that second drive. Data can be spared.

I would do it a tad differently though. Use Macrium to CLONE the OS from the SSD to the M.2. Then shut down, physically pull the cable off the SSD then reboot. You will likely have to tell the system in the BIOS to use the M.2 as the boot drive.

Once it's up and running satisfactory then create a file in the root of the C: drive and name it M.2.txt. Shut down again, reinsert the cable on the SSD and reboot. Check to see if you are actually booting to the M.2, is the file in the root of C: named M.2.txt? Then you are there. If it somehow booted to the old SSD then you need to fix the system to NOT do so. I've seen more than one person do a clone, boot up and then wipe the wrong drive. Not a biggy if the clone worked as it should, a disaster if it didn't.

After you are sure the M.2 is working then download MiniTool partition wizard and use it to remove ALL the extra partitions off the SSD and then resize the old OS partition. At this point you can delete all the old stuff from the original Windows OS by deleting it. Leave the DATA you want to remain on the drive.