You can use the search button in the bottom navigation bar to search for communities but as far as I know it's still pretty bare bones.
Proper search for keywords isn't implemented yet, but this is a well known issue and addressed on GitHub.
See:
Jerboa is a native-android client for Lemmy, built using the native android framework, Jetpack Compose.
Warning: You can submit issues, but between Lemmy and lemmy-ui, I probably won't have too much time to work on them. Learn jetpack compose like I did if you want to help make this app better.
Jerboa is made by Lemmy's developers, and is free, open-source software, meaning no advertising, monetizing, or venture capital, ever. Your donations directly support full-time development of the project.
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You can use the search button in the bottom navigation bar to search for communities but as far as I know it's still pretty bare bones.
Proper search for keywords isn't implemented yet, but this is a well known issue and addressed on GitHub.
See:
I am not sure whether it works for communities you have yet to subscribe to, but below everything else there is the second button on the left (with those horizontal bars). It leads to a list of communities you are subscribed to, and is "topped" by a search field.