(disclaimer: this is my first project ever so I'm not very knowledgeable and might be missing something obvious).
I have a project that I prototyped with an uno and now want to move to a nano iot.
It uses I2C as communication and the components in question require 5V.
Everything is connected through USB cable to my computer.
The project works like a charm on the uno where I'm hooked into the 5V pin. I modeled it to use the 5V pin on the arduino as well but it is consistently outputting around 2V as measured with a multimeter linked to GND and the 5V pin.
I tried the multimeter on the uno and it registers about 4.8V so I think the multimeter itself is working fine. I had another nano still boxed up and tried that (just in case I damaged the nano I'm currently using) but it too registers +-2V when measuring 5V to GND.
You need to enable 5V pin with a solder bridge. Or better, power your 5V "components" from 5V power supply.
So they quite probably use 5V on I2C as well and you need level shifters for that to be compatible with 3.3V Nano.
Feel free to post your "components" here.
5V on that pin is available only when two conditions are met: you make a solder bridge on the two pads marked as VUSB and you power the NANO 33 IoT through the USB port.
Take note of this important note at the beginning of the document linked by @camsysca
You CAN NOT directly connect any device that will put a 5V signal on any of the pins of the Nano 33 IOT. A device that takes 5V for power, and uses its own regulator to obtain a 3.3V operating voltage would be ok to use.