Use the Institute for Composer Diversity. Though they have not created a special section for Chamber Music yet, you can search their Composer Diversity Database to identify composers who have written chamber music. TIP: Scroll way down on that page to find the search you need! I show you how to do this in the video below.
You can also use the Composers Equity Project list, provided by Chamber Music America. On this list you can view ALAANA composers. ALAANA stands for African/Black, Latinx, Asian/South Asian, Arab/Middle Eastern, and Native American. Note the diamond symbol which identifies gender non-conforming composers.
Notice that Earsense chamber music database has a separate list for Black composers. Their Advanced Search also offers you other ways to find repertoire, such as gender.
There are MANY other sources for finding music from composers by viewing the Online Resources tab of the guide Beyond the Canon: A Guide for Finding Repertoire from Underrepresented Composers and Overlooked Music.