I wrote an extensive post on the topic that the forum ate because I'm not allowed to post links. So that is super annoying.
A short summary :
en.wikipedia DOT org/wiki/List_of_infantry_divisions_of_the_Soviet_Union_1917%E2%80%9357#People's_Militia
armchairgeneral DOT com/rkkaww2/formation/DNO DOT htm
provide lists of the extensive PMU formations raised at Moscow, Stalingrad and Leningrad. Leningrad could justify two garrisons and a corps. Moscow could justify 4 to 6 corps and an Engineer. Stalingrad could justify a Cavalry Corps.
These events would be similar to the Volkssturm events for the Germans. When the Germans close into within ten tiles of these cities, they start spawning units.
There should be some events related to women in the RKKA, PVO and VVS. The standard thing to do is to spawn the 588 Night Bomber since that one has a long history in Soviet propaganda, but you could do a lot more. Svetlana Alexievich's The Unwomanly Face of War (Amazon has a kindle version in English, buy it) has substantial first hand accounts from women in every arm of the Soviet military, including in front line roles as tank crew, infantry, air defense operators and snipers among many others. It also discusses some of the more "Me Too" style elements of the experience. An event related to the huge number of women that signed up and attempted to sign up would be a nice recognition of their service and of the unique status of women in the Soviet armed forces.
The Soviets should get a couple of events related to the massive crash mobilization undertaken in 41. Where the Wehrmacht was depleting reserves of every equipment type and had run dry on replacements (meaning trained recruits available for service in existing units) before starting Typhoon, the Soviet military replaced itself three times over and still managed to grow in size! Surely an event is warranted here.
An event for the formation of SMERSH would be a neat note.
On the cultural side, it'd be neat to see some recognition for Vasiliy Grossman and other front line reporters, as well as some mention of some of the big propaganda films that got put out in this era. I'd link some but holy heck this forum is rude about links.
There's more, but writing the same post twice isn't exactly fun so....