There were programming books "Made in GDR" sold for the Spectrum (I still have most of them), sometimes without mentioning that it comes from the West. Never saw one about Commodore or Schneider.
Popular, but rare given the price you had to pay (around 5000.- East German Marks, average income around 500.- EGM) if you were able at all to purchase one on the black market. But still cheaper than a C64 or CPC (up to around 15.000.- EGM), sometimes sold in so called "Intershops" for (West) German Marks to.
Even the KC-Series from our own production were hardly to get for a private person - so more or less Homecomputers in general were rare and so not very "popular" in the GDR.
Fun fact: First announced as HC 900 (HC for HomeComputer) the officals changed the name to KC 85/2 (KC for KleinComputer, SmallComputer) cause they realized that they could not satisfy the home market.
I dont know of any East German C64 or CPC games either... for the same obvious reason.
There was some (commercial) software for the KC though but still far less than for the Western ones.
BR / Andy