Comment by Terr_

> I'd say C++ is the least suitable for "learn on the job" approach out of any language I can think of

Anecdote: I've got a couple languages and decades under my belt, and a very simple C/C++ Arduino project is making me doubt my sanity. Ex:

    Serial.printf("%s", String("Hello world...")); // Emits 4 nonsense bytes... But shorter literals work fine.

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EDIT: To save readers some time--I didn't intend to nerd-snipe [0] y'all, honest!--the answer has been found, and it is probably:

    Serial.printf("%s", String("Hello world...").c_str() );

The shorter payloads like "Hello World" happen to give the desired results only as an accident of optimization code.

[0] https://xkcd.com/356/