Probably a power issue. Make sure to use a good USB cable, or feed the board externally or via a powered USB hub.

What board do you use? What did you flash to the ESP32, and how? What power supply and cables are you using?

You don't; heap essentially is all the free amount of memory you have left, you can't expand it. Just make sure you're not using up heap space elsewhere, or are doing silly stuff like filling the entire internal memory when you still have PSRAM left where you can move stuff to.

A VCXO would work fine then. Do note that the RTC internal to the ESP32 has no battery backup option, though; if the ESP32 loses power, it also loses it's understanding of the time. If you need this, it's probably better to go the external RTC route.

Yes, both are hardware peripherals, and (apart from some details wrt what pins to use if you need to go *really* fast) they are fully interchangable.

If anything, esp_http_client_read doesn't zero-terminate the string it receives; instead, it returns its length as the return value. ESP_LOG, however, assumes the string is zero-terminated. As it is not, ESP_LOG will happily print any crap that's after the end of the string, including perhaps a back...

In one transaction (I think you call that a frame; the time when CS is active), you can send/receive any amount of bits, from 1 bit all the way up to 16777215 bits (however, you don't have enough RAM to store the latter amount), and anything in between, with a granularity of 1 bit. As such, 32 bits ...

We would certainly applaud anyone who tries, but the reality of having two cores and a plethora of complex communication protocols (WiFi, BT, BLE) plus the layers on top of it (LWIP) make it much, much easier to approach problems from a thead-based point of view, hence our choice of FreeRTOS instead...

Yep, it worked hahaha :D So the ESP32 DOES have 3.3v and 5v output. Much thanks! Note that the ESP32 itself does not. Your devboard probably has a secondary chip to allow it to work on 5V as well, but the ESP32 by itself will malfunction and potentially release the magic smoke when you try to power...

SPI itself doesn't have the concept of 'word size', it just reads in a stream of bits. The ESP32 hardware then reformats these bits into 32-bit words, but that's just a method of storing information. As you can store a bitstream that is as big as the ESP32's free memory, the bit size is more-or-less...