i have thought about using the CH376 (which is an upgraded version of the CH375 with built-in FAT32 support) for generic USB devices, but there is not a lot of documentation for it.

one alternative would be the CH32Vx Microcontrollers. they're similar to other 32-bit MCUs, but they use a RISC-V core instead of ARM and are able to directly run with 5V while other MCUs like STM32, Propeller, or RaspPi Pico can only run at 3.3V (though STM32's have some 5V tolerant IO).
plus they seem a lot cheaper... the lowest end STM32 i could find with a USB host controller is the STM32F102, which is ~5 USD (mouser). while the CH32V103 is ~1.50 USD (lcsc, useful when ordering from JLC).

you could then try to port tinyUSB to it for the bare metal USB stack to make writing drivers for various devices easier.