As far as I know, A 1 is required for a family reunion visa. Unless you have a particularly high academic background and basic knowledge of German, you can answer the visa officer's questions smoothly. The time they give you is really short, because this material is not attached, so you should prepare it before you submit all the materials. So it's definitely too late for you to take the A 1 exam now.
But A 1 is not very difficult. I don't know where you are. At present, many places have A 1 exam training institutions, the most authoritative of which is the Goethe Institute, which is located in Beijing, Guangzhou and Shanghai. The patterns of the papers are almost the same. As long as you master the methods, you can easily pass them. Please come quietly when you study A 1. Don't just think about how annoying this exam is, think about a good convenience. Mainly to adapt you to life in Germany, which is very practical. People with A 1 level should be able to understand all kinds of broadcasts in public places and simply ask for help.
I suggest you get the certificate of A 1 before submitting your application.