I´ve already played four games with URSS since the patch two with Germany with full bonuses. The first one Germany attacked in Summer of 1940, as soon as the non-agression pact can be dissolved. It really made sense as they had already conquered the rest of Europe. However, in the next playthrough I didn´t move my divisions back to the Dnieper as soon as they started their focus and just stacked everything in the border. That prevented them from breaking the pact (As they didn´t have 200% divisions than me) and weren´t able to do so till a year later, when you can disband it if you have similar forces on each side. So it kinda worked historically for me if I just didn´t concede fighting on the border.
Can´t speak about the IA though, I just did a short trial game as China in this patch and I didn´t play very long.
Also in the game Germany attacked minon 1940 was by far one of my bests HOI4 SP experiences. Germany attacked me way before I expected. They crushed my army and pushed all the way back to Moscow and Leningrad. I barely held the line in northern Russia at the gates of Moscow and I was to stall the war from there. A winter and a half later, attrition massive casualties in failed offensives had worn the Germans down and I was able to slowly push all the way back to Warsaw and later to Berlin. It arrived a year early, but it was my most "historical" Barbarrosa vs an IA by a long shot.