Several of us have a HAPI-like interface for ingesting data into a server. What's nice about this is since the API for reading is clear, it's usually pretty clear how upload would be supported as well. This is far from being a standard HAPI feature and may never be, which is why it is described here.
My first use of this was a raspberry pi HAPI server, where I wanted a way where a script could push data into a server, instead of writing files which the server would read. Lewys asks if there's a way to do this on this thread: https://groups.io/g/hapi-dev/message/597. Eelco does this already with his server, described here: https://gitlab.com/KNMI-OSS/spaceweather/knmi-hapi-server/-/blob/main/doc/API.md?ref_type=heads