How are mineral cast double washbasins installed?

We will have a drywall T-wall construction in the bathroom, and the washbasins will be attached to it. For budget reasons, we will purchase an inexpensive double washbasin with mineral cast from the internet. Now the question arises: how will we fasten these lighter (than ceramic) basins? I suspect that due to the stopcocks + drain, we will need to install two of these usual (e.g., Geberit Duofix) mounting elements in the T-construction. However, these now have the usual threaded rods for ceramic basins!?
I have often found that the base cabinets are dowelled to the wall and the washbasins basically just rest on them. So if I now leave out the threaded rods in the mounting element, I am basically losing the possibility to hang a ceramic basin there again at some point, right?

Construction foam :D Sorry, I couldn't help myself :(

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We also installed this cheap version with the base cabinet directly dowelled to the wall. I only have the threaded rod version in the guest bathroom, I don’t use it because I also mounted the base cabinet, as it is more practical and provides more space for stuff.

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Question 1) So is the information from the internet true that mineral cast basins usually rest only on the cabinet due to their low weight? For ceramic washbasins, whether with or without a base cabinet, these threaded screws from the mounting element are used to take the weight. I can't really imagine that a double washbasin (even if it is mineral cast) together with a base cabinet can be held up with just a few dowels in a drywall wall.

Question 2) If the mineral cast tops are not hung on these threaded rods, how can I best "prepare" so that I can later attach a ceramic top? Does anyone have a setup where they have a mineral cast top with the threaded rods hidden directly beneath the washbasin in the base cabinet?