Not a native English speaker, but an English teacher. In my experience, “shall” in the sense of “will” is practically never used in American English, and it’s slightly archaic but occasionally still encountered in British English. (Think of Churchill: “We shall fight on the beaches, we shall fight on the landing grounds, … we shall never surrender.”)
An outdated (and even in its time probably inaccurate) grammar “rule” says that the future is expressed with “shall” in the first person, and with “will” in the second and third person - and that be reversing this (e.g. “I will”, or “he shall”), you are adding emphasis and/or intentionality to the meaning. However, this is categorically false today, and probably always was. (Note that even the Churchill quote above disregards this “rule”! According to this rule, to demonstrate determination and intention as he did, he should have said “we will”!)
American English does use “shall” in the phrase “shall we [do XYZ]”? It’s also used very frequently in legal texts, in the sense of “must/must not” (as in the Ten Commandments: “Thou shalt not…”, or as in the 1st Amendment to the US Constitution: “Congress shall make no law…”)