After some reading I think the ADF won't solve anything because the problem is not audio, but in the bluetooth.
The more proper question I think is:

Can the ESP-32 be a central bluetooth device?

I tried to use the example a2dp_source in the IDF to connect to a BT speaker but it won't find it.
Am I missing something or do I have to use ESP-ADF?

Any quick pointers on how to modify the A2DP-SOURCE to:
- Just connect and keep it connected
- Use I2S as input

I just built the a2dp example and flashed it into the DevKit but it finds an error and resets.

E (572) I2S: /home/joan/esp/esp-idf/components/driver/i2s.c:838 (i2s_param_config):I2S communication format invalid.
E (572) I2S: I2S param configure error

I found somewhere it's 4.2, is that right?

All the question is the header

I would like to stream audio to the ESP-32 from a PC or phone. I suppose this is possible, is there any example application to base myself on? Also, is there any limitation in the audio formats?

Have you checked those few boards don't have a short causing that before thinking about more esoteric possibilities?

That clarifies a bit, but is not what I was looking for as I'm not thinking of making my own builds, I just wanted to be able to get any build release I might need without having to trust the power of search engines

Sometimes when building an example or project, I found that message :

WARNING: Toolchain version is not supported: 1.22.0-XXX
Expected to see version: 1.22.0-YYY

So far, what I'm doing is looking for it and finding some link, but isn't it in git?