I just tried the code from the tutorial, modified only to comment out the DHT code, and use a random number for temperature. Installed mosquitto on a Raspberry Pi. Installed android app on my phone. Works fine here, temperature updates display correctly on my phone. No error messages in serial monit...

Yes, you can serve HTML files. Of course, you'll need to learn how to use the file system, and how to handle file operations like create,read,write,etc. There's a lot to learn, and you won't learn it all by asking on forums. School is good, and books. Probably easier to start with a real OS, Raspber...

Is the assumption that this is caused by electromagnetic interference, and NOT by noise or sag in the power line?

Just to be clear - are you saying it isn't getting to the loop checking WiFi status?

Works at home, not at office? Different make/model of WiFi access points?

Going back to your first attempt, exactly how were you doing delay of .125? That should work, if you use delayMicroseconds(125).

If you use delay(0.125), the float 0.125 will be silently converted to int 0 , and it won't work.

I'd try running WiFiScan to verify that radio reception works, then try connecting to an open AP.
But, of course, your device may be defective.

I just ran SimpleWiFiServer here, works as expected.

Did you set your ssid and password correctly?

At the very least, your final snippet doesn't allocate any space for
char * s;

So, s is a pointer which doesn't point to any storage.

Reading a capacitive touch pin returns an analog value which varies with capacitance. To use it, compare that value to a threshold.

Note: they don't all return the same value when not being touched, so I'd use a few reads to calibrate the threshold value.

Have you tried any other pins?

I just got a Nodemcu 32S a few days ago, and have had success using I2C on 33=SDA, 32= SCL, running an SSD1306 128x64 OLED display.

-Robert