Looking for someone who can assist in accessing GPS RINEX data
(pseudo-ranges etc.) from one or more popular smartphones (iPhone, any
Android device, etc.).

Is there anyone out there that knows how to do that ?

[typer]

You need a gps-receiver that can record pseudo-ranges. This is normally not done on phones or other low-range gps-receivers.

There have been people able to record raw-data from old garmin devices and also newer sirf IV chips. Otherwise, receivers cost from approx USD 350 (ublox lea-6t) and upwards.

The raw-data can then be converted to rinex with f.ex. rtklib.