New Offerings not in Heist?

I kinda liked the challenge of the new Harvest-Labs. They seem to be gone for now (unless the Offerings drop during Heists/Grand Heists). Or did I miss something?

No, you are right. Winged Scarabs, Infused Beachhead, Infused Labyrinth and pretty much anything Harvest-related will not be in core, thus inaccessible in Heist. Unless, as you stated, Heists/Grand Heists somewhat offer that as a reward

Back at standard you can still access them provided you put those items in a stash before Harvest end