War & Military - 32 free documentaries about ukraine & russia.
Start with 2000 Meters to Andriivka (108 min, FRONTLINE PBS), then 20 Days in Mariupol (94 min, FRONTLINE PBS). All 32 documentaries here are free to watch from their makers' official uploads. To read deeper, the top-rated book on ukraine & russia is The Gates of Europe by Serhii Plokhy.