Hey, very cool app. One thing that could be a massive improvement is the ability to tap the thumbnails in "compact mode" to open a bigger version of the image without loading the whole post. Boost (for reddit and for lemmy) has something like this (though not as snappy as I'd like), and relay for reddit had the perfect implementation of this. It was quick and easy. You tap the thumbnail to blow the image up to the max screen width, tap again to dismiss the image. Ideally there would be no lag between when you tap and when the image is loaded, same with dismissing. (I disabled double tap in relay so the image dismissal didn't wait for a 2nd tap, making it quicker.)
Obviously this is a very nice and niche feature, so it might be outside the scope of the app. But if you find yourself itching to add some features, keep this in mind :) It would fit well with the "fast, fluid browsing" theme of the app.
I took a video to give a quick example but uploading it to lemmy.world isn't working, I don't want to share my youtube account, and I don't want to make you download a random file from a file sharing site, so you can check out this behavior in those 2 apps if you need an example.