Hi Arcady,
Like you, I was glad when Steinberg included Ambisonics in Nuendo, and, like you, was disappointed when I noticed that Blue Ripple Sound plug-ins didn’t work in Nuendo. You can circumvent this problem by hosting the Blue Ripple Sound plug-ins in a Plogue Bidule plug-in hosted in Nuendo. Not ideal, but workable.
That being said, there’s two suite of Ambisonics plug-ins that do work in Nuendo and that are quite comprehensive and actively developed: SPARTA - Spatial Audio Real-Time Applications and https://plugins.iem.at