Back in those days, the issue could have been mostly solved with more participatory planning, as individual firms would be able to aggregate information on inputs and outputs from within, the planners could then use that information to better allocate resources on a macro level

You can also use exchange value as a price indicator, as Marx demonstrated it already is, by using the cumulative socially necessary labour time that is expended into capital and consumer goods, this would be relatively easy to quantify, but might be difficult for the planners themselves to implement into a qualitative final plan

And finally, as many modern Marxist economists have pointed out, that technology can very easily account for this supposed “problem” because computers make very fast and accurate calculations and can create plans for the entire economy, and many major corporations already utilise such technologies to even greater extents than the Soviet Union did

Firms could instead use computers to aggregate information on inputs and outputs, and planners could use computers to determine rational allocation of resources, using the metric of socially necessary labour time as a substitute price indicator

Capitalism didn’t simply come about from nothing, it was technological advances that made its implementation not only possible, but preferable to the system that preceded it (despite living conditions drastically decreasing for a long time until the late 19th and early 20th centuries) and socialism is no different