As far as using QSPI memory, one thing I have planned (and will be thoroughly testing) is using an external SPI flash as configuration data storage. Right now if I want to store any nonvolatile settings with power loss protection I need to burn two 128 kB erase blocks (one primary and one secondary, so I can ping-pong data between them and not lose anything if I have a power loss during a write cycle or similar) of the on-chip flash, space that I'd much rather use for firmware.

MicroKVS expects to be able to memory map data fetches (uncached), but is fine with using indirect access for writes.