Just a quick update here. Today I had some time, so I managed to add a hall sensor to my Pinecil V2. Now on the soldering stand equipped with a neodymium magnets at the right spots (near the point where the tip is inserted to the soldering iron, under the green rubber handle) the iron gets into sleep mode, showing ZZzzzz on the display. This is especially handy when power is scarce, for instance when doing the soldering off the power bank. I do not do this too often, but it is usually when doing some car repairs with the battery disconnected.

The Pinecil V2 PCB without the hall effect sensor populated

For the job I used the SI7201-B-00-IV which I had lying around for some time. It is not recommended for new designs, but hey, for something like this, it is perfectly suitable.

The Pinecil V2 PCB with the hall effect sensor populated

Not the greatest soldering I have ever done though. Enjoy!