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You need an M5Stack device, like the Basic Core or the Core2 ESP32 IoT Development Kit. GREY and FIRE devices can also be used but they don't add value. You can buy it from the vendor, on AliExpress or online sellers like Amazon.
You will need Wi-Fi or a smartphone allowing Wi-Fi tethering since internet access is mandatory.
A micro SD card is optional if you want to have different sets of settings, it doesn't need to have a large capacity. When booting the M5Stack with an SD memory it will use values from it, else it will use those in the device memory. Newer M5Stack Basic and Grey don't like SanDisk Ultra SD memories, try Kingston or some no-brand memories, 16Gb or even 8Gb (and less) are more than enough.
If you don't want to keep your device permanently connected to and USB charger (having one is mandatory but any charger will do) you'll need to buy one ore more battery extensions. See this for normal battery lifetime.
The USB cable provided is very short, you might want to buy a longer one if you prefer to keep the device connected all the time. The cable is USB to USB-C.
You need a computer to program your M5Stack.