Hello
The YAMAHA NUAGE for post production is the best tool with Nuendo, but I know it’s expensive. I bought mine used. But It’s really a sensational tool with Nuendo.
Otherwise an S1 or an artist control + mix works well, and the EUCON protocol is very well recognized by Nuendo. On the other hand it is difficult to make quickly EQ or send manipulations for example.
Finally, there was the SmartAv Tango that I know with Pyramix and it was very good stuff, but it is no longer produced (ask Fenderchris for more details)