Meanwhile, in the 1950s and 1960s nuclear power was going to be the Next Big Thing, and it was understandable that low-efficiency PV tech was of interest only for things like satellites. IMHO, the top-down energy policy managers that couldn't fulfill the "too cheap to meter" promises of nuclear power wouldn't have been up to the task of accelerating PV technology either.
Solar cells are not like gas lasers, which could have been built in a neon-sign shop in the 1930s if the science needed to steer the technology had been in place. They are more like practical neural nets. Sure, they could have been built in the 1960s... if only GPUs weren't so darned hard to come by.
(And as someone else suggested, any nation that began the 20th century by pouring the resources into PV cells and EVs that we put into fossil fuels wouldn't have lived to see the 21st.)
Similar story for lithium batteries. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7215417/ seems to be a decent survey of their evolutionary timeline. They consist of multiple discrete technologies. R&D that goes into a good cathode has to be done separately from work on anodes. Same for electrolytes and separators. Looking at the bibliography in that article, batteries don't seem like the sort of field where progress could have been accelerated just by throwing money at it, and I think that's true for PV tech as well.