Samsung might be done tinkering with the ARM core designs, as the Mongoose proprietary cores appear to be missing on the upcoming Exynos 9830. The Korean giant is rumored to drop its two homegrown high-performance cores for a couple of ARM Cortex-A77 cores in order to better match the Qualcomm competitors.
https://www.notebookcheck.net/Leaks-suggest-upcoming-Samsung-Exynos-9830-SoC-will-only-use-ARM-Cortex-cores.437549.0.html
The mongoose cores were not derived from Arm designs.
Apple's volume certainly justifies their R&D...