These uav's are not that hard to make.
Unless you are trying to do something almost impossible, like achieving 30k feet flight altitude with usable payload using 2 piston engines( Tapas/rustom 2) to save "cost" , while all others just went with turboprop engines instead( now new indegenious engines developed for tapas are turboprop, and engine used in archer-ng is also turboprop).
Once HTFE-25 is developed, we have all the tech needed to make a HALE stealth UAV, so ~ 2030 is what I think for entering service.
