[goombacloud]

There is a changed version that includes drop-in config files, masking, and loading defaults from /usr/ instead of requiring full config files to live under /etc: https://uapi-group.org/specifications/specs/base_directory_s...

[gioele]

There is work going on at freedesktop to standardize drop-in config files:

«basedir: support separate (vendor/local) trees and masking for config files» https://gitlab.freedesktop.org/xdg/xdg-specs/-/merge_request...

«basedir: support drop-ins for configuration paths» https://gitlab.freedesktop.org/xdg/xdg-specs/-/merge_request...

[account42]

This is much less general since what it means to merge configuration files is extremely domain specific.