$10 worth is on average 3 bottles (average of big/smalls) a month.
That is because wholesale average of big/small is around $3.25 ($4.50 + $2.00 divided by 2).
So this is about on average 1 bottle every 10 days. We know some stores sell a bottle a day, others maybe one a month, others maybe not active anymore.
Approximately 4,000 of the 5,000 stores are in Canada. The USA has approx. 10x the population of Canada and with the likes of Home Depot also 10x the stores.
So 'if' WNBD could get similar retail penetration in USA as Canada it is reasonable to think that it could do 10x the results it is currently doing in Canada.
So if 1 person in Canada buys one bottle every 10 days. 10 people in USA could buy 10 bottles in 10 days in USA (a simple statistical math equation).
If sales in Canada are approximately $500k of the $600k you state; then 10x that number would be $5 million.
I think 1000 Do it Best outlets could get us $1 million in USA by themselves. Lowes/Home Depot activation on shelf nationally would easily complete the other $4 million (the quickest way imo).
But there are other ways to get USA penetration (Duane Reade/Walgreens, Sams Club, Office Depot, Tractor Supply, Farm Fleet, Menards, Ace Hardware, True Value, CVS, etc.)...in some of the most populous states and cities in USA.