The HC-05, a Bluetooth to serial bridge, can be found for around $5 on the internet and therefore may be the cheapest way to add Bluetooth connectivity to your project. However, its default setting… ...

The wireless power behind the new Arduino comes from a custom ESP-32 based module from u-blox. There’s also a tiny crypto chip (Microchip’s ATECC508A) so the Uno WiFi will work with AWS.