That's a bit rough as a price tag for an esp32s3 board... They've been available with lcds included for $20 for quite a while at this point. Bare they're around 10-15$.

It has Bluetooth, Wi-Fi and an IMU built in which is very useful for a robotics project I'm currently working on. Plus it has a huge amount of RAM and flash compared to an ATMEGA Arduino

Seconding this. Just not having to muck about with a second board for the IMU was worth it for me, but also having wifi onboard at a time before the pico W got released was good.

Can you post your recommendations? I'm looking to build some stuff for fun, like DIY CO2 sensor.

Say I go for something else than Arduino, what am I missing out on?

https://esphome.io < find a board + sensor pair here. Software stack tested with your board+sensor is hard to beat.

ESP32 boards: surprisingly fast/powerful little SOC with wifi

ESP8266: cheaper+slower. I like the Wemos D1 mini board: smaller and has enough horsepower for most things.

Sourcing: a ton on options on AliExpress. Buy a few extras so if you fry one you aren't waiting for replacements. They are super cheap ($3-$6).

Options to consider for board: memory, CPU speed (ESP32 vs ESP8266), size/form factor, pins/dev board or just solder holes, does it have built in USB controller (and which one), voltage regulator for 5V, USB Micro vs USB C, sensor voltage requirement, etc. Sounds complicated, but they are all pretty similar, and can typically buy a few and make your projects work. Getting one of the "branded" options like Wemos D1 is good bet, comes with all the basics covered, and no surprises like making your own voltage reg.

Sensors: lots to learn on each one. Just did the deep dive on CO2, and there were a ton of details (eCO2 vs CO2, auto calibration quality, manual calibration support, cost, airflow, etc). Went for Senseair S8. If you want easy place to get started, look at AirGradient Kit: https://www.airgradient.com/kits/

I'd recommend staying away from the 8266s at this point. The chip is EoL and the ESP32 offers double the speed, more than double the IO pins, and bluetooth. The 8266 is limiting with its single ADC pin, and single hardware serial and inability to define other pins for I2C/SPI.

I started with the 8266s thinking I wouldn't need the extra features, and most of my applications don't need it, but the few times I needed to work around the limitations weren't worth the aggravation to save $1-2.

All true.

But I love how tiiiiny they are :)

Arduino's have a lot of documentation and a great platform. The language is basically C and there are lots of libraries available so most sensors should be easy to get running.

I don't know about the RP2040, but the ATMEGAs can't multitask and have pretty low resolution ADC.

In my experience having them calibrated properly is a pain in the ass because they rely on the input voltage and that changes slightly depending on the method of power input.

A computer using USB will give you a different result than on battery power since the USB is going through a diode but no regulator and the battery is going through a regulator or straight into the 5V line. To make it work I ended up cutting the voltage lines on a USB cable and connecting a battery for power.

I'm sure there is an easy way to deal with all that stuff but I'm not good enough to have figured it out.

The RP2040s can multitask. This is because the Arduino compatibility layer is actually built on top of MbedOS which support preemptive multitasking. You have access to the full API set of MbedOS in addition to the Arduino APIs when the code is running on an Arduino RP2040.

You might get the most fun for your buck with an ESP32 Cam or EYE. ESP32 Cam boards go for about $7-9 on Amazon if you buy 2-3 at the same time. They don't have built-in USB, so you have to use an FTDI or other UART adapter to flash programs to it (at least the first time, you can set it up for OTA updates afterward). The more expensive ESPEYE has USB built in and a more powerful processor. The Seeed Studio ESP32 units also look interesting.

Here is a tutorial about how to use TinyML to perform image detection on the device: https://dronebotworkshop.com/esp32-object-detect/

An actual Espressif ESP32, or the Arduino Feather variant if you want QUIK connectors for most sensors (if you can’t solder etc, or want to use plugs to make it serviceable).

Both are cheaper than this yet are the same thing.

> Can you expand a bit on the value for the money?

When compared to other Arduinos, probably.