I wonder if Lemmy's (and thus the Fediverse's) target audience is even willing to spend money on apps. Even the makers of Tweetbot are having a hard time competing with Ivory against the numerous free alternatives.
If the target audience you speak of is people leaving the other site and coming here, then I'd say 100% yes. I can only speak for myself, but after seeing what they did to Apollo, I would be more than happy to spend some money to support Christian if he were to make an app for Lemmy. I think a lot of others would to.
There were no really good free Reddit apps for iOS. Apollo hit a niche. A free Lemmy app would at least have to compete with Mlem and the time frame is narrow until the market is flooded (see also: Mastodon’s three months from 0 to 7262952 apps).
Hopefully mlem gets new features added. I don’t know how to subscribe to new communities on it or see replies to my comments so I use the browser as well.
I hope they add compact view. I like knowing the exact boundaries of each post or item on the feed. With the way that posts get expanded based on whether it's a text post, image, or link, it makes it hard for my lil brain to digest.