Is there an Arduino library, for ESP with at commands ?

Hardware Arduino Zero
7

Juraj:
RingBuffer exists in SAMD core and in WiFiEsp

Since WiFiEsp uses the correct #include syntax, I don't see anything that would be problematic about that at a glance.

Juraj:
implementation of functions with variable arguments length are not compatible with ARM compiler

I noticed that from the error messages in the previous reply. I guess that needs C++11? It should be resolved by:

but there doesn't seem to be recent progress on that. It's kind of funny that the relatively modern SAMD boards are using a more outdated toolchain than the old school AVR.