The LG Stylo 2 plus from T-mobile (K550) and Metropcs (MS550) will be getting updated to Android 7.0 Nougat Very soon, Since LG has just published the source code for LG Stylo 2 Plus Android 7.0 Nougat software.
As you can see from above screen shot, The Android N V20a Software source code for T-mobile LG Stylo 2 plus (K550BN) and MetroPCS Stylo 2 plus (MS550) is available for download.
The Update is not out yet, Looks like that LG is still testing the Android N firmware for Stylo 2 Plus, and T-mobile official website does not mention the Android N Update.
For your information, The current software for LG K550 is K55010r (Android 6.0.1) which was released on March 23, 2017. The LG MS550 received the MS55010r software update in March. It is t is actually just Marshmallow and the February security patch.
Remember to bookmark this page, we will add the Android N 7.0 kdz firmware for LG Stylo 2 in this post when it is available for download