The Russian war economy is too tight to support military R&D on top of the existing war effort. GDP per capita is way too low and military brass aren't willing to discuss the subject of their own vulnerabilities to Putin. Their use of oil money to buy Iranian drones is a necessary kink in their supply chain since they don't have the means to build their own drones at scale and they can't develop industrial capacity for the same without jumping face first into the woodchipper of sanctions.
Remember when Putin said the invasion would take 3 days? Deception can be tactically useful but not when you're the one lying to yourself.