The last few years have seen a scatter of articles about Surge, Xiaomi's supposed competitor to the Kirin or Exynos SoC series of the world in development. Now, however, there are indications that the Chinese OEM is finally giving up on this idea. However, it will continue with other, related projects that may produce chipsets for wireless communications.
https://www.notebookcheck.net/Xiaomi-reportedly-abandons-all-hope-of-an-in-house-CPU.458547.0.html
It's not technical difficulties, it's financial difficulties. Xiaomi's profit margins are much thinner, and they don't have lucrative infrastructure contracts awarded to them for political reasons to transfuse into a semiconductor project. Indeed they didn't invest nearly as much into Surge as Huawei did into Kirin, and other chips for that matter.