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As Vasile Eftodil says, the Arduino is a good starting point using C++. The Arduino boards are available with either AVR microcontrollers (the majority of boards) and ARM (Arduino Due) controllers. https://www.arduino.cc/ Arduino boards are widely available so it shouldn't be a problem. Third party boards are also widely available since both the hardware and software are open source. You won't need to use VSCode and PlatformIO with them either because everything is contained in the Arduino IDE.
Choose C then C++. Most frameworks and examples are written in these languages. You may start with Arduino or ESP32 from Espressif using a development board. You may try install VSCode and the PlatformIO extension for the development environment. Then try to write some simple program to connect to WiFi, publish some data with MQTT protocol, use UART, etc. A good understanding of electronics and microcontrollers is required though. 😉