Source: https://borecraft.com/files/intro-composite-temp-white-paper-345213.pdf
Composite Temperature is a single, normalized temperature value that considers input from multiple temperature sensors ... while reporting to the host a single Composite Temperature value for thermal management.
... does not necessarily represent the actual temperature of any physical point within the SSD.
Composite Temperature works by monitoring multiple temperature sensors at regular intervals and comparing each current sensor value to a pre-set maximum value.
(The) NVMe recommendation of 70C is referred to as WCTEMP or Warning Compositive Temperature Threshold.
You can see that it's not a temperature in the traditional sense, but a reference that informs the host system or user ... before it (the SSD) reaches a thermal limit.
More info in the NVMe specifications: https://nvmexpress.org/wp-content/uploads/NVMe-NVM-Express-2.0a-2021.07.26-Ratified.pdf
I tried locating some NVMe SSD's schematic or some manufacturer information, but that seems to be very rare:
That leaves the option to look at some NVMe SSD (CORSAIR Force MP510 in this case) and try locate SMD sensors to get their actual locations which I did for some random SSD. In this example the sensor seems to be located closely to a NAND chip:
For your particular SSD you'd need a high resolution picture from both sides, or examine the SSD under a microscope. For this purpose a digital microscope may be easiest. Use this as reference for example.
I am not certain all sensors may actually be in the form of a separate SMD component.
It still leaves the question what Sensor corresponds with Sensor 1, Sensor 2 etc.. My best guess would be (I know you're not asking for guesses):
Temp - Composite
Temp 1 - Controller
Temp 2 - NAND or board SMT (?)