Does a “smart” switch need a neutral wire?

I am now at the stage of repairing an apartment in a new building from scratch (at the design stage of the project so far), all wiring will be redone at least because the walls will move. In the apartment I want to put “smart” Aqara switches that will be integrated into the smart home system.

There are two versions of these (and other smart) switches - the version with a zero wire (zero line) and the version without zero. The difference is that the first one holds more load (up to 2.5kW) and can count energy consumption. The second one holds only 800 watts, does not know how to count consumption, and it needs one less wire. In general, I do not need electricity counting, and the power of 800 watts for chandeliers is more than enough IMHO.

Nevertheless, the manufacturer by default recommends the version with zero as the main one and supposedly if the wiring is done according to the rules, then there is zero in the switch for any. These statements confuse me, because I do not quite understand why zero is needed in the case of conventional switches? And if you do the wiring, then I want to do it standardly like everyone else, and not for specific switches .. I’d better pick up the switches for the wiring. There are also concerns - will there be any problems with the RCD if zero goes through these switches.

I took off the existing switches in the apartment and looked - there are two wires to the one-button switch (as I understand it, the switch simply breaks the phase) to three-button switches.

In general, I am in doubt, please advise which option is better to stay on?

There, among other things, I was also embarrassed and this comment made me think, but I don’t know how true it is, because I didn’t fully understand the idea. But the potential problem with RCD is alarming (quote from the forum):

Cool! But all this will work if only the electrician did the wiring everywhere correctly! And the zero for all groups should be common, otherwise if you take zero from another group protected by an RCD, for example, it will not work, since the RCD will detect the leakage to the lamp through the zero of the socket group! And I think that these are such grandiose discounts on Ali that came to these switches (well, at least the Chinese signed the zero fire line), but people ran into difficulties and are not happy ...

P.S Here is another comparison of switches with zero and no zero line in English, but from the video and so on, everything is clear:

Illustration of connecting switches (on the left, one-button with zero, on the right, two-button without zero):