First electronics project: ESP32 + DHT22 + OLED — what do I actually need to get

[tooki]

A diy continuity tester would be an awesome first project.
I have one which has a high-bright LED as well as a buzzer and with decent probes, it's instant.

I'm sure the probes are the expensive part of the project.

Indeed!

Leo's ultimate continuity tester is a great design (google it for both the original Youtube video, but also several third parties who've documented their own PCB layouts, etc).

I made a version of it a few years ago, and with modified capacitor values (to improve response time) it's great. I've been meaning to design a variant with a latching beeper to avoid scratchiness while maintaining detection speed.

[Peabody]

My projects are almost always battery powered, and the low sleep current of AVRs makes a difference.  And from my memory, ESP32s do not return to the next instruction after waking from sleep.  They reset on wakeup.  Also, AVRs retain GPIO state during sleep.  I don't think ESP32s do that, at least not reliably or by default.  Another problem I found, which may have changed, was finding good datasheets on ESP products - info on registers and such.  For understandable reasons, that was particularly true for the ESP8266.  I don't know where things stand now with the ESP32.  And then there's the watchdog timer, or should I say timers, which you can't shut off.  I'm not a beginner, but I find the ESP stuff difficult to work with despite being very powerful.  But mainly, it's the sleep current.

[negativ3]

A diy continuity tester would be an awesome first project.
I have one which has a high-bright LED as well as a buzzer and with decent probes, it's instant.

I'm sure the probes are the expensive part of the project.

Indeed!

Leo's ultimate continuity tester is a great design (google it for both the original Youtube video, but also several third parties who've documented their own PCB layouts, etc).

I made a version of it a few years ago, and with modified capacitor values (to improve response time) it's great. I've been meaning to design a variant with a latching beeper to avoid scratchiness while maintaining detection speed.

I quite like the scratchiness of mine, it means connect better dummy 

[tooki]

A diy continuity tester would be an awesome first project.
I have one which has a high-bright LED as well as a buzzer and with decent probes, it's instant.

I'm sure the probes are the expensive part of the project.

Indeed!

Leo's ultimate continuity tester is a great design (google it for both the original Youtube video, but also several third parties who've documented their own PCB layouts, etc).

I made a version of it a few years ago, and with modified capacitor values (to improve response time) it's great. I've been meaning to design a variant with a latching beeper to avoid scratchiness while maintaining detection speed.

I quite like the scratchiness of mine, it means connect better dummy 

The thing about a fast latched continuity tester is that you can make audible transients that are too short to hear! (And in really smart, fast continuity testers, like the one in a Fluke 87 V, can also latch discontinuity, extending the pauses in continuity from an intermittent connection, for example.)