You will probably get more traction on r/AskElectronics.

As far as starting and learning, here is a decent place: https://www.codeproject.com/Articles/1223855/Practical-Electronics-For-Makers-Part-of-N

Here’s a popular book: https://www.amazon.com/Practical-Electronics-Inventors-Fourth-Scherz/dp/1259587541

You can get some starter kit sets also on amazon for not much expense: https://www.amazon.com/REXQualis-Electronics-Breadboard-Resistor-Raspberry/dp/B078XV3RK2

Beacons are just a small portion of BLE, and honestly, not the meat and potatoes portion. You can download nRF Connect by Nordic Semi on a second phone and mock BLE device interfaces. But a cheap hardware solution that is pretty easy to work with is the ESP32 based boards, this one works very well:

https://www.amazon.com/HiLetgo-ESP-WROOM-32-Development-Microcontroller-Integrated/dp/B0718T232Z/ref=sr_1_10?crid=36J6S4ZEL973M&keywords=esp32+ble&qid=1648776975&sprefix=esp32+ble%2Caps%2C108&sr=8-10

If you add a breadboard, a 5V/3.3V power supply board, and some buttons and wires you can make something that you can interact with to trigger events that are notified back to the phone. It can all be done in Arduino IDE using C++, but for simple stuff it is pretty easy to hack things together. This kit would give you everything else you need to make some interesting test devices with the ESP32.

https://www.amazon.com/REXQualis-Electronics-Breadboard-Resistor-Raspberry/dp/B078XV3RK2/ref=sr_1_3?crid=1HSZSDV5COHB0&keywords=breadboard+kit&qid=1648777293&sprefix=breadboard+kit%2Caps%2C109&sr=8-3

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If you choose to go this route, feel free to reach out if you need any tips or pointers, I can even throw together a sample program for the ESP32 if you want.

Edit: Also, if you want to mess with Beacons, a simple solution if you have a second phone is the app Beacon Simulator by Vincent Hiribarren. There may be other ones that work well, but I have personally used that one and it hasn't given me any issues.