If there are borders in space then spacefaring peoples have learned how to demark them. Don't overthink it because the people in universe already have done.
Re-watching seasons 1, Chapel got a retroactive level of badass this season. In All Those Who Wander she was capable but not prepared, being somewhat out of her depth. Since this season gave her a war veteran background with M'Benga she's more specifically combat ready.
When you think about it, SNW Chapel is already so far removed from TOS Chapel character-wise that they might as well have let Jess Bush just run with a 'new' character. I mean, other than the name and the fact that they are in the medical department, they don't really share any other traits. If they wanted to, she still could have had all the relationship hijinks with Spock. Most episodes she comes across as a more competent medico than the CMO.