What technology would help the Imperium the most?

Im well aware of the classic line: "Forget the power of technology and science, for so much has been forgotten, never to be relearned."

I read that to say no feasible amount of technological development will be enough to save humanity. If you read that to say Imperium technology can never improve, then lore has already broken that with the Primaris and their shiny new equipment. While it can be debated on how Primaris equipment stacks up against the best equipment on offer during the Great Crusade, there is no debate that the Primaris Marines themselves are a significant technological improvement over the Astartes that came before.

When I talk about what technology would help the Imperium the most, im largely talking about feasible technological improvements, in the same way that making stronger and tougher Astartes was feasible. The Mechanicus is not going to suddenly master and replicate Necron tech, and the Webway project will almost certainly never be completed.

While im sure there are no end of civilian technologies that would be an immense help, and I would appreciate any suggestions on that, my attention is drawn to military equipment.

To me, I believe the reintroduction of Volkite weaponry would be an immense help with the Imperium's current primary foes. The Emperor at one point planned for volkite weapons to become the standard issue weapon of the Imperium, but the technology wasn't mature enough to make that logistically feasible and resources were needed elsewhere for the Great Crusade. The Astartes did make frequent use of volkite weapons at first, but later switched over to the bolter for more versatility.

That last part seems to me a function of the enemies the Imperium was primarily facing during the Great Crusade, Heresy, and immediate aftermath. The capability to completely disintegrate any matter at a reasonable distance seems like it would be immensely helpful in the 42nd millennium.

While Heretic Astartes are still a major threat, volkite weapons offer little benefit for Loyalist Astartes in this case, as bolters are effective and there is no need to disintegrate their bodies. That said, volkite weapons would be extremely helpful for Guardsmen to counter traitor Astartes.

Im thinking instead about the Necrons and Tyranids. For the Necrons, the explosive charge of a bolter round is little use against an enemy with no organs to concus, and lasguns do little to necrodermus. A Volkite weapon would be an immense help against the Necrons, ironically mirroring their gauss weapons, as one shot would be enough to progressively disintegrate a necron soldier, and can even spread to other nearby Necrons that have little inclination to dodge away.

Against Tyranids, the use case is obvious. While not ideal against swarms of smaller forms, it would be effective at disintegrating the biomass of larger forms, denying the Nids their strongest advantage of winning the battle of attrition through reclaiming every killed unit.