It takes about 30 seconds for the US National Debt clock (https://www.usdebtclock.org/) to tick off $1 million, so almost 2.5 days to tick off $7 billion. I'd say $7 billion covers much more than 3 seconds of interest.
It does improve it, by several orders of magnitude. If your point is strong enough to make without exaggerating, then use of hyperbole can only stand to distract from the point.
I mean... so I just noticed the "US Total Interest Paid" clock. That takes about 45 seconds to tick over $1 million, so $7 billion covers ~1% of the interest payments in a year.
That seems like a sizable contribution for a single person in a country of 330 million.
Great, so now all we need is another 99 people with similar donations and we could cover the interest for a year. Then you need to continue to do that every year forever because you have yet to make any movement on the principle