Here is my comparison of the Rode NT USB and the Shure MV88. Both recordings are in WAV format and no processing or adjustment has been done on the files.
The Shure was connected to an iPhone Xs and the recording was done using the MOTIV app. The Rode was connected to an iPad Pro and the recording was made using the Rode Rec Lite app. Both mics were placed about 18 inches from the guitar at about the 20th fret; the mics were side by side and a single performance was recorded.
The piece is "If You Were Here" by Per-Olov Kindgren. The guitar is a double top by Gary Lee strung with Augustine Regals.
Here are the links to the files:
Rode NT USB