I have had my fair share of trouble with the LAN8720.

The layout of your boards looks okay, but why is the clock so far away?

What I would recommend is to try:
- analyse your clock and check for noise
- get the clock from the ESP32
- try adding hardware reset (not sure if you have it on the board ...

Just use and rename your main.c to main.cpp

I'm currently using multiple protocols like BLE, WiFi, Ethernet, MQTT ect.

The BLE part is used for configuration and used 2-3 times in the lifespan of the device. Other protocols are used all the time.

Because other peripherals require quite a lot of heap, I'm looking to expand it as much as ...

I had recently switched from platformio to esp-idf.

Platformio was very handy in the way that I could define which release version I wanted to use for each project. This also helped when other people wanted to compile my code.

What is the best practise with esp-idf to do the same?