Berlin WW2 Historical Archives Research of the Occupying Soviet Red Army

I am currently in Berlin conducting research on a specific Soviet Red Army soldier who was involved in the capture of the Reichstag. This research is a for a potential article I am considering submitting for my own record. The research costs and efforts are therefore borne by me alone. I am specifically looking for any old German databases or old Soviet Red Army archives which may list the soldier and his activities. In summary, I am looking for any evidence of what he did while he was here. I am using this to both validates parts of my article and also build a profile of his life. I have significant details about his life, family etc, including photos of him in military uniform etc. Yet, I do not have much actual evidence of his time in Germany. I am looking for someone with deep archival skills who can (A) very quickly do an initial search to determine if a (B) deeper search is necessary. I will be with my research assistant in Berlin until 20 July 2026 and I am hoping to make some progress while here. The ideal researcher should understand the German and Soviet-in Germany archives and possibly speak German, understand Russian and speak English. I would also like to visit some of the archives with you.