Do I need to stay in my home country while my DTV visa application is processed?

Question about DTV application locations.

Hi everyone, I'm hoping someone can share some insight here.

I'm applying from my home country, where I'll be spending a month prior to flying back to SEA.

I'd like to book a flight to HCMC at the same time, so that I can avoid a last-minute flight.

Does the applicant need to remain inside the country of their application for the duration of the application process?

Or is applying from the home country and then potentially only obtaining the visa while in Vietnam doable?

Thanks :)