[foota]

A columnar database format might perform well out of the box in that case.

Reading more, it seems like a columnular database built on LSM trees would probably work great, since you could easily move the log around in flash to distribute write wear out, and only occasionally compact LSM tree files.

[ComputerGuru]

It would, but there are any small and simple enough to use in a standalone (no-OS, non-POSIX) environment?

[foota]

I found https://github.com/embassy-rs/ekv after some searching, but who knows how battle tested it is.