Ukraine

Ok you are mixing up a couple of different things here.

Ok first, no, this is a common misconception with High Explosive Anti-Tank munitions, especially sophisticated ones like the RPG-7 that I imagine has actually gotten a decent amount of people killed from believing it. This was a big thing in attempting to up armor Strykers and other armored vehicles in Iraq and Afghanistan for the US army since the threat of RPGs was so prevalent, and the brutal reality is unless there is a specific counter to a specific warhead such as some of the slat style armor on Strykers that was designed to fuck up the contact sensor on the RPG warhead, detonating a HEAT round before it impacts armor actually IMPROVES the armor penetration of the molten hot jet formed by the HEAT round.

In general I believe HEAT type rounds perform best when they have about a meter or of space to form a molten jet, so detonating a HEAT round before the armor proper is actually a problematic proposition. For a typical main battle tank HEAT round this kind of detonation before the main armor on this shitty "tank" would likely do nothing for survivability in the best case scenario.

This ‘bird cage’ (Figure 1b) put around the vehicle exploits a specific weakness in the design of the detonation chain of two of the most common antitank rounds for the RPG-7 system, using, respectively, the PG-7 warhead (the oldest and likely most proliferated antitank ammunition for this system) and the PG-7M warhead (based on the same functioning mechanism as the original PG-7, but having a smaller maximum diameter). Next to these two very widespread types of ammunition, a number of other Soviet types of ammunition work on the same principle, e.g., the PG-7L warhead also for the RPG-7 weapon system, the warhead of the RPG-18 disposable antitank rocket launcher, and of the SPG-9 recoilless rifle.

Contrary to what many may believe, the main defeat mechanism for the PG-7(M) warhead, when fired against such a cage armour system, is not based on an increase in standoff distance, as with the so-called ‘bazooka plates’ from World War II (Figure 1c). A simple comparison between the two types of protection clearly shows the much more complex (and hence expensive) geometry of a typical cage armour system when compared with the simple sheets used for the historical bazooka plates, which would have sufficed if the goal was only to create standoff distance.

https://www.mdpi.com/2076-3417/12/10/5064

Perhaps the most common myth which has arisen around HEAT warheads is that they can be easily defeated through the use of small amounts of standoff (empty space), with popular opinion frequently considering a gap of 0.3 m to 1 m to be sufficient to nullify the penetrative power of the jet. Once again, this is mistaken, as can be readily seen from footage of overfly top attack (OTA) weapons such as NLAW, which often activate their warheads at more than a metre over their target.[15] Nonetheless, common arguments that standoff defeats HEAT warheads have pointed to the adoption of spaced armour, including side skirts, and statistical armour protection such as bar armour (also known as slat armour), and RPG netting (such as Tarian) as proof that standoff is somehow effective against HEAT warheads. Again, these are largely inaccurate, and have arisen from a fundamental misunderstanding of how such forms of protection actually work.

To understand why, the first thing to note is that HEAT warheads actually require a relatively high degree of standoff distance just to reach their maximum penetration potential. The exact optimal distance will vary depending on various factors in the warhead design, such as liner material, liner angle, liner thickness, liner grain size, defect tolerance in liner manufacturing, explosive filler type, detonation wave shaping, along with various other factors, and will vary among different warheads. However, as a general rule, it is not possible to get the maximum level of performance out of a jet without a degree of standoff – simply put, some physical space is needed for the jet to focus itself into the optimal shape.

https://euro-sd.com/2024/06/articles/38841/the-most-misunderstood-weapon-in-the-world-mythbusting-heat-warheads-and-their-countermeasures/

The PG-7VR round is intended for engaging all types of tanks (including those protected with ERA), armoured and soft-skin vehicles and for suppressing of enemy`s manpower inside building and installations. It is equipped with a tandem high-explosive anti-tank (HEAT) warhead. According to the specifications, PG-7VR has a caliber of 105 mm, a weight of 4.5 kg, an effective firing range of 200 m, and a penetration capability of more than 0.6 m of homogenous armour.

The PG-7VL round is intended for engaging all types of tanks (including those protected with ERA), armoured and soft-skin vehicles and for suppressing of enemy`s manpower inside buildings and installations. It is equipped with a HEAT warhead. According to the specifications, PG-7VL has a caliber of 93 mm, a weight of 2.6 kg, a maximum effective firing range of 300 m, and a penetration capability of more than 0.5 m of homogenous armour.

https://armyrecognition.com/focus-analysis-conflicts/army/defence-security-industry-technology/analysis-russian-defense-industry-rpg-rocket-propelled-grenade-launchers-and-rounds-12201173?highlight=WyJydXNzaWEiXQ%3D%3D

https://armyrecognition.com/military-products/army/anti-tank-systems-and-vehicles/rocket-launcher/rpg-7-russia-uk

Second, main battle tanks such as the Abrams or Leopard use Armor Piercing sabot rounds. They aren't chemical, they are massive hunks of sharp metal, they don't care about some fluff in front of the armor plating or reactive/explosive armor meant to disrupt the formation of a HEAT jet, they will punch through all of it just the same. If a freight train is hurtling towards you, derailing the train just before it hits you isn't really a defense as you still have a freight train hurtling towards you.