Ask HN: How should I Help Ukraine?

I am the primary developer of some open source Android applications. The most popular is UserLAnd, https://play.google.com/store/apps/details?id=tech.ula . I am personally upset by the further invasion of Ukraine by Russian forces. I am trying to think of what ways I should respond to it. I am genuinely seeking advice. My current thoughts are to: 1) Modify applications to have a political statement, like "Ukraine is not Russia" or "No war please" in Russian for Russian users. 2) Give financial aid to the Ukrainian defenders. 3) Pull my apps from Russia. (I like this the least) I have a small audience and limited resources, but I am determined to do something. What are your thoughts about how I should go about this?