Your hood would need to be high enough to cook under; the gap to dishwasher would have to comply with the induction unit's installation manual; space for any insulation needed would have to be included; and, because many induction units have a cooling fan, the source of air for the fan would have to be room temperature and not hot dishwasher boundary air.

If the intent is to mount the induction unit and its support surface above an existing uncut counter isolating it from the dishwasher, then the installation manual will provide needed information. Cooktek, among many others, make units that sit on counters, so examples of the heights needed can be found there as well as for other lower cost options you might find by searching. Whether 10 cm (4 inches) is sufficient space I cannot say; no induction unit I have owned was that thin.

Portable units using 120v plug-in power sources in the US can be used without a raised platform. Check for similar for your local system. And look for another use space, as a dw is usually right next to the sink. For a function oriented cooking setup, I'd pair that with an air fryer/toaster oven.

What size induction cooktop are you planning? A 30" cooktop would require cutting the sides of a 24" dishwasher cabinet to fit it. The Frigidaire FCCI3027AB cutout height is 2-7/8" so it might sit right on the countertop but check the installation instructions.

The induction hob specs will have certain vertical clearances that must be met, for electronics ventilation. That's why they usually have a false panel in a drawer base, or a deep drawer base that does not allow usage to the drop dead point. I have done this with a 24" mini hob, for an Airbnb mini kitchen, using a short ADA DW, with the legs cranked down to have space at the top, which was filled by a trimmed filler. But it is a nope to a 30" with a standard DW mounted directly underneath the counter area with only maybe 4 cm of air space.

It might work if you have the clearances. I would be concerned about the heat that the dishwasher might put out (especially if you have / use heated drying) adding heat to the space that is usually used to dissipate heat for the electronics under the induction surface.

Minardi: "The induction hob specs will have certain vertical clearances that must be met, for electronics ventilation...But it is a nope to a 30" with a standard DW mounted directly underneath the counter area with only maybe 4 cm of air space."

The installation instructions for the Frigidaire FCCI3027AB do not state that any space is required below the cooktop for ventilation. Why a 24" cabinet top could not be cut to accommodate the cooktop is unclear.

"using a short ADA DW"

If the OP doesn't hasn't purchased a dishwasher this is a good idea. The Bosch SGE53C55UC ADA dishwasher is 32 1/16 Inch high while the standard SHE43DM5N is 33-7/8" high.

Just as a general commentary, several manufacturers in the 1960s-70s made a unit that was a DW underneath, a cooktop and an eye-level mounted oven. I am not sure if the DW had to have a lower interior cabinet. Maybe but we had a Chambers electric cooktop that was narrow enough to have a drawer immediately underneath (1969)

This was apparently a solution for kitchens that had no dedicated space for a DW.

There's no reason that supports couldn't be added to the cabinets on either side of the dishwasher opening to support the countertop. It would be little different than adding a platform to a cabinet to support a rangetop. Plus, the Frigidaire cooktop cutout depth is 19-5/8 inches deep so 4+ inches of the sides of the adjacent cabinets remain to support the countertop.

The hob may weigh 35lbs and a full 16qt. stock pot 32lbs. This wouldn't break counters I'm familiar with.

Then you aren't familiar with all the fissured stones coming to market than need better than average support under them for the fissures to not become cracks. Like Taj Mahal. And others.

Minardi: "Then you aren't familiar with all the fissured stones... Like Taj Mahal"

An ai search for "Support Requirements for Taj Mahal Quartzite Countertops" did state "No unsupported spans longer than 24–30 inches" and to avoid " Floating dishwasher gaps without a support rail". However given that the Frigidaire cooktop cutout depth is only 19-5/8", it might be possible to add a support rail behind the cooktop. I might be possible to add a rail in front of the cooktop if a short, ADA dishwasher were used.

Electric cooktop next to the sink what could possibly go wrong , sorry just a really bad idea.

The drain hose for the Bosch SGE53C55UC ADA dishwasher can be as long as 92" so the sink wouldn't necessarily have to be adjacent to the cooktop. It would be interesting to see the proposed layout of the kitchen and its appliances.

Waiting for a floor plan and pictures which is the only way to really understand why .I assume you are not in the US so probaly the best is to check with codes where you live .

When you say "hob", do you mean a standalone/portable induction hob similar to one of these?

If so, what do the specifications say for the hob you're considering?

For what it's worth, I agree with Patricia that an electrical appliance like a hob right next to a sink is a very bad idea! (Assuming the DW is next to the sink.)

*sigh* Another "drive-by".

So much effort, so little reward.

Really I have no idea why they ask for help.