At this moment plus a tense

At this moment, I am working at Walmart.

Can we use "at this moment" even if I am currently at home or no and we would only use this time expression when I am actually working?

It would be clearer if they said "at the moment, I work at Walmart"; however, it isn't unusual for native English speakers to say "I am working at [x]" to mean they are currently in that employment and not that they are engaged in work at that precise moment in time.

The statement isn't helped by the use of "at this moment" (or, more commonly, "at the moment"), which is often just a flowery way of saying "currently", but if taken literally it could sound like right now, as we speak. As above, native speakers wouldn't necessarily take it literally, and - as always - context is everything. If someone told you they were "working in Walmart at the moment" and they were anywhere other than in Walmart at the time, you should know it isn't literal.