Production way of OTA updates using ESP32

[follicle]

Hi, folks
I am working on a project that will use ESP32-WROVER-B to read data from several sensors and send to a server. My colleague has a version of it which works from gsm/gprs modem by connecting to the internet accordingly. However, what I need is wireless (OTA) update mechanism.
For now, let's already assume that there will be multiple systems (ESP32 microcontrollers & sensors) and a single router together with repeaters covering some area. In order to connect to that router and establish connection to & from microcontrollers assume we use VPN tunneling or static IP address assignment, no problem.
The question is, what is the production way of implementing OTA update mechanism in my case?
There are several ways to do that. What I am thinking of right now is to continuously run webserver on each ESP, waiting for a moment when admin will enter correct login credentials and upload the binary file. Once the upload ends, ESP will restart. Basically, I will be able to update specific ESP microcontroller, plus now I have to send sensor data using wi-fi, no need for gsm/gprs modem. So, does it mean my program now has 2 threads of execution? Does my idea even sound realizable, or there is a better way to implement that?

Any professional advice and/or suggestions would be appreciated!