I don't think "slingshot" is the right analogy here. There is a big change towards intelligent, small, and cheap drones. If it were just a slingshot, other countries could pick up what Ukraine is doing in no time, but they can't. Instead, there's an absolutely massive industry behind Ukraine's drone manufacturing, growing at 2x per year, which no other nation can currently match, including Russia.
The drone manufacturing has gone so exponential that they now have a shortage of drone operators. It's completely changed the war in the past few months, with Russia now losing ground, at basically zero additional Ukrainian casualties, and with Russia continuing to have massive ground casualties from sending poorly trained troops to die while hiding in a 30 mile wide kill zone ruled by drones.
The quantity of drones allows new tactics, reminiscent of rolling wave artillery. And deployment of a wide variety of types of drones has led to the depletion of Russian anti-air defense in both occupied Ukraine and in Russia itself, allowing the destruction of much of Russia's oil infrastructure. The recent Baltic port hit will be felt for a long long time, and nearly completely neutralizes the lifting of sanctions on Russia. All from novel weapons, which are decidedly more sophisticated than slingshots both in their construction and application. And the US is way behind, and too proud to let Ukraine share their knowledge and capabilities.
