Good morning everyone,
Correction. When I wanted to measure the milling cuts precisely this morning, I unpacked the larger board. And lo and behold: two pure white cardboard boxes appeared, including countertop connectors, Lamello, and two tubes of sealant (I guess similar to silicone).
It would have surprised me a lot if Ikea sent one separately to the specialist trade. Actually, they do offer everything for their products.
All the more relieved I can now concentrate on the installation.
Thank you very much for the answers and the quick feedback.
Have a good day.