Here are dome ways non-developers can help:

Give issues that affect you a thumbs up on the issue tracker (GitHub in this case). Same for feature requests on the issue tracker. This shows the developers what things people want them to work on. They may not do so, but it enables them to make an informed decision.

On a related note, don't post comments like "this affects me too" on the issue tracker. A thumbs up indicates this and having a long list of comments like that risks people missing something important.

Help with testing and add any details that are missing. Steps to reproduce the issue are critical. Other examples: "this bug doesn't affect Android 13 and below" or "introduced in version xyz".

Be concise with your comments.

Link related issues together. Often it's helpful to know about other issues when a developer is already in that section of the code working on something else. Plus, it can help avoid making one problem worse when fixing another.

Creating a bounty is a good one, if you can afford it.

Spread the word about the project. I know this one sounds cheesy, but the more users a project has, the more likely it is that additional people will help with all of the things above (or people you share it with might be developers who can help with the code).