Every minute there is no PWA, this is a potential loss of 20 percent sales on the busiest and fastest growing channel. A simple calculation: when a webshop has a turnover of 20 million per year, it misses about 1.4 million by waiting a month to implement the PWA. When you wait half a year this is 6.8 million.
However, this does not take competition into account. When not switching to a Progressive Web App, not only potential customers will be lost, but the competitor's SEO score will also be higher due to the improved webshop.