ᐅ Ikea Fyndig Kitchen Wall Cabinets

Thanks for the information!
I went to IKEA yesterday and then to the hardware store, and I will now install them using the standard mounting rails from the hardware store (which was even the advice given by the friendly IKEA staff).
This is probably the simplest, most straightforward, and likely the most affordable method.

Do you have a drywall partition, or why do you need the rail?

From the hardware store, I only know

together with

Overall, this tends to be more expensive, but using the METOD rail requires that you can get the METOD hangers as spare parts. Other uses, meaning not as spare parts, are not intended, so a furniture store may not want to order these parts and might refer you to an outlet or the hardware store.

Those are exactly the ones I looked at in the hardware store as well.
The problem is that the wall is 1. uneven and crooked, and 2. the pipes aren’t clearly detected even with a stud finder (old building). To get a good result, using a rail like that is the most practical option, and it gives me more flexibility when drilling the holes. I’d rather invest the 30€ (about $32) than risk drilling into a pipe or having the cabinets hang crooked on the wall. 😉

I also had a similar experience with the cable locator. It lit up almost everywhere. I ended up drilling where it didn’t light up and hit a cable 🙁

The first time, we thought the device was broken because it was really lighting up everywhere. And when we found a "safe" spot, marked it, and checked again, it lit up red again. Unbelievable 😀
So we ended up with triple safety: wire detector, mounting rail, and logical thinking about where the cables should be running. It should be fine 😉