USB drivers — explicitly called out as a pain area with the current vendor; needs dedicated in-house depth (host controller, device/gadget, USB compliance & low-power modes).
PMIC area — flagged as significant but difficult; requires focused, specialized hiring since talent is scarce.
PCIe — identified as one of the major areas where issues arise; must be a core competency.
Adjacent low-level buses / peripherals that naturally cluster with the above: I2C, SPI, UART, clock/regulator framework, storage (UFS/eMMC).