Like the coulometer they mention. This is a battery discharge sensor, nobody would mention this in the specs. SAR sensor and coulometer are standard by now.

Which leads to a conclusion, either the makers don't know enough to know it's standard (which suggests they aren't well informed enough to make a modern smartphone), or they do know but decided to include it to pad their spec sheet (which suggests disingenuous marketing).

They could just be transparent and know their techy customers are interested in these sorts of things. Possibly, they want to assure customers that their off-brand phone includes such features.

That would also be my reading. I'm the type of nerd who's interested in minute details of his devices. I'm looking for a new phone currently and my spreadsheet includes columns like the UFS version, minimal brightness (as measured by some independent news site), whether it has a barometer, dual-frequency GNSS, etc. It always requires retrieving info via third parties such as https://docs.google.com/spreadsheets/d/1jXtRCoEnnFNWj6_oFlVW... (GPSTest database), https://phyphox.org/sensordb/, the video mode list on gsmarena.com, etc.

I haven't yet found a manufacturer that publishes sufficient detail such that I can fill out all relevant columns from their official spec page. They're never detailed enough so I can only applaud including more details. There will always be fields that aren't relevant to different subgroups of the audience...

> by detecting whether the phone is held close to your body vs. sitting somewhere like on a table

Wow, so it basically measures the material that it's near to! That's cool. I know that microwaves are well-adsorbed by water (such as in bodies), is that how this works, does it piggyback on the 2.4 GHz antenna? Can I read this sensor's output via some Android API or a device file (with root perhaps)?