Wait, since this is the second week for Octopath Traveler, does that mean that at that point it had a 65% digital attach rate since it was announced that it sold 1 million digital+retail just 2 weeks after release?
No, absolutely not.
First off, VGC's estimate is 450k boxed copies sold, so that alone caps digital sales at 55% in the best case scenario.
Secondly, the announcement for 1m was made on August 3rd, so that would be four weeks of VGC tracking, not two. Another 100k physical copies sold in each of week 3 and 4 caps digital sales at 35% in the best case scenario.
Thirdly, publishers count physical games as sold as soon as they got packed up and are on their way to retailers, so in the case of Octopath Traveler we have to account for copies in transit that hadn't even been put on shelves to be bought by gamers. Additionally, the game wasn't sold out in every place in the world, so there were definitely units sitting on store shelves as well. Everything together means that 30% digital sales is the highest reasonable estimate, but the limited information makes it more sensible to use a range as estimate for digital sales, so anywhere between 20-30%.