Good luck controlling an 8 pin relay with 4 accessible pins hah.

The 01s are cheap for a reason - they're useless for most projects, hell I'm always running out of pins even on the esp32-cams.

The ESP01 works perfectly for most sensor projects. It can handle I2C and serial IO simultaneously.

If you really need more GPIO you can get an I2C based IO Expander to add 10 more GPIO.

Meh, those cost extra and don't really do analog in or PWM out and have dreadful response time. Plus you have to deal with i2c which adds complexity.

I suppose in this case you could do it in that roundabout way by stacking two of those for relay control since it's as basic as it gets.

Do you mean this? https://www.amazon.com/CANADUINO-WEMOS-Minikit-240MHz-Blueto... because it has a lot more than 4 accessible pins.

Nope, I mean this: https://www.amazon.com/MakerFocus-Wireless-Transceiver-DC3-0...

8 pins, half of those gnd, vin, reset, and something else. 4 are usable I think.

That's an ESP-01. It has 4 GPIO with some restrictions but you are able to simultaneously run an I2C bus and Serial bus giving you tremendous flexibility.

You can get those in bulk for less than a dollar each and are my most used microcontroller. They're so easy to deploy and ear easily powered of USB wall warts with a regulator.