Just want to confirm this solution as working for M5Stick-C and M5Atom... I'm on latest macOS 10.15.3 (19D76).

OK - replying to myself just to provide information for further researchers.
The repo https://github.com/crankyoldgit/IRremoteESP8266 works just fine (I used theirs IRMQTTServer example). compile it specifying 17 as kDefaultIrLed and that 's it. But - I've found that IR works only if I place it very very close to the subject. ie to control my AC I have to place it say in 20 cm to its IR receiver... that was really unexpected....
@m5-docs so question is - I use default parameter for IRSend library which assumes usage of 50% duty. can I increase duty to 100% safely (w/o risk to destroy IR Led on my M5Stick or on M5StcikC - I have both) in order to increase distance?

@m5-docs thanks for pointing on this. digging the rabbit hole ended at this repo: https://github.com/crankyoldgit/IRremoteESP8266. very cool. very stable and very active to the moment.
but unfortunately my m5stick(gray version) nor stick_c (orange version with color lcd) does not work with it.
I used G17 for gray stick and G9 for stick_c as ir_pin - no luck - my mitsubishi AC does not respond to sent requests.
I wondering if I need change anything in IRremoteESP8266 code to make it run over IR or what is the way to verify IR on stick or stick_c works properly.
Specifically - the IRSend class in IRremoteESP8266 just uses:
pinMode(IRpin, OUTPUT); -> to start
and
digitalWrite(IRpin, outputOn);/digitalWrite(IRpin, outputOff);
to ledOn and ledOff

while FactoryTest.ino for stick does this:
ledcSetup(1, 38000, 10);
ledcAttachPin(IrPin, 1);

So my question is - are these two calls significant or I can ignore it?