Don’t get lost implementing fancy features at the beginning, concentrate on supporting what the Lemmy web UI does and try to provide a smooth and pleasant experience on iOS.
In case you’re looking for inspiration would highly recommend to take a look at the Ice Cubes client for Mastodon. An extremely well made app.
Germany, yes we do drink water without boiling it directly from the tap. Tap water must in general have drinking water quality across the country. However, even it may not be a health risk, some people don’t like the taste. Where I live, it tastes very good.