Former Shopify iOS dev here. I pushed SO HARD to get dark mode to be a thing we would do. It's table stakes, IMO, in 2020 and beyond, to support it. We'd get roasted on Twitter, LinkedIn, just about everywhere. HN Comments, even. :)
Got shut down at the highest level. Like, definitively. As in, please don't ask again.
I don't think you'll ever see it as long as Tobi is CEO.