(assuming you are in the US). Go to Amazon, buy an ESP32 beginner kit, which should come with an ESP32 dev board, a handful of different sensors and components, and a breadboard and some wires. It will also have some sample code.

Go through a few of the basic modern IoT "hello world" examples, like making a web-enabled temperature sensor. Then google for "ESP32 [foo]", where foo is some random idea that you have for pretty much anything you can imagine that has even the remotest reason to be internet-connected.

Assuming that you are comfortable with at least semi-advanced software development, learning basic embedded stuff with ESP32 or Arduino is pretty easy. There is no operating system, or heavy stack, which can sometimes make things like a Raspberry Pi more overwhelming to start with in terms of embedded stuff.

For learning, Adafruit and Sparkfun have a lot of good material. Lots of nice hardware too that one can buy. Hackaday is a good place to visit couple of times a week to find interesting stuff. Then there are many good YouTube channels for learning electronics as well, search the internet for some tips and try some of them out.

I can recommend Mouser, DigiKey and RS-Components.

AliExpress has been surprisingly great. Good selection. Great prices. Just make sure to buy from reputable sellers.