I use Firefox for Android. It works perfectly, everything is usable, good UX, has dark mode, and the app even works for other websites!
You can even install the ublock extension to block all ads & trackers in opened links, or use it to block large images by default to save data. And you can install the tampermonkey extension to add this userscript I made, which rewrites all links everywhere (not only on Lemmy) to always point to your home instance. It helps a lot with subscribing to communities and in general makes browsing the web and finding Lemmy links nicer.
I honestly don't see the reason why you'd want to use a separate app.