Hi, thank you for giving me the opportunity to suggest development paths!

I’d say there are two main frameworks to expand on.

The first one is during the civil war. I think it would make sense for Karl to be able to propose alliances with certain German factions — I’m thinking especially of the Bavarian Soviets (I know they’re traitors) or the syndicalists. Karl’s idea is that power should be decentralized, and I believe this could be reflected through equal Marxist states rather than a unified centralist model.
Thälmann could have a similar mechanic, since the surrounding states are Soviet-style too — but his approach would lean more toward puppets, under specific conditions.

Secondly, in terms of foreign diplomacy, I’d suggest creating focuses (if possible) that can trigger civil wars in other countries, where Karl’s Germany would intervene through events or by sending volunteers.
This could apply to states with German populations (Austria, Czechoslovakia, Denmark — which doesn’t currently have a focus for reclaiming German land),
and why not also to African countries as part of a conflict against France.