There may be delays, but nevertheless I've been getting my domestic eBay
purchases within or before the estimated delivery window. On average, they've been taking about a week. The only exceptions have been when the seller is slow in putting the stuff in the mail (I occasionally buy from a seller who was notorious in this regard even before COVID-19 gave them an "excuse"). Even purchases from the U.K. have been reaching me in California in 10-14 days.