The use of the word STINT?

Stint can mean a period of time but usually time spent working. Eg He did a two hour stint in an Amazon warehouse. A long stint drinking coffee doesn’t sound right unless meant in a humorous way.

Or in a different context, but still denoting a period of time. As in, he or she did a stint in the military after high school.

Yes

I’ve only ever heard this in the context of doing a job, either as employment or a chore.

For example; I am going to do a stint in the yard (meaning that I am going to work in the yard for a while), or I did a stint as a truck driver a few years ago.

I wouldn’t use it in the context of a casual or leisure activity.