Hello Christopher-deHaas,   QinQ will be release for 10.5.4.0 code. I do not have a release date.   I hope this helps.  
I cannot find any information about QinQ support for Dell OS 10. Is there any way for OS10 to understand QinQ or is it simply not supported? If it is not supported, does anyone know whether it is on the roadmap?
Dell OS10 QinQ