Without really revealing a lot about the plot, during Captain Marvel, Carol Danvers is exposed to the Tesseract, and it grants her a lot of powers and energy manipulation. This feat had seemed amazing to someone like Fury, and it looks to have actually fuelled his agenda when he had taken over the control of S.H.I.E.L.D.
It has been revealed in the very first Avengers film that SHIELD had been in possession of the weapons manufactured by HYDRA using the Tesseract, and they also had blueprints to make many more. However, if this theory by u/Britator on r/fantheories is correct, then the aim of SHIELD’s research had been more sinister than what the Avengers unveiled.
This fan suggests that SHIELD had never really been trying to create weapons out of the space stones as the Avengers had thought. They were also not trying to use the Infinity stone as a source of unlimited and sustainable energy.
The space stone had been analysed by SHIELD to create super-powered soldiers like Carol Danvers. The idea is that SHIELD had been trying to resurrect the super soldier program which had created Steve Rogers and this time, the secret was not super soldier serum but the Tesseract.