IKEA over here sells just separate ovens and cooktops while other brands offer both connected style and separate oven and cooktops.
They often sell separate oven and cooktops as set's which makes them cheaper.
One big reason I stear people towards separate ovens and cooktops is that if either breaks, you can replace just one.
With induction cookers, the power electronics in the thing often just give out after 5-10 years while many even cheaper ovens last easily 10y or more.
The sets cost pretty much the same no matter if you get it with the knobs integrated in the oven or with separate controls for both.
Technically, manufacturers often offer some form of cross-generation drop in replacements so you could just buy a separate cooktop and just replace that.
But these are usually prohibitively expensive and for some mysterious reason *cough* every 5-8 years the connection standards between oven and cooktop change so you can't replace one of both.
Thus it's just easier to buy both separately.
Oven and cooktops usually run on 3 phase 1 neutral.
Each phase gives 240V to neutral at 16A, just about 3.6kW.
Your cooktop is usually split in 2, one large and one small burner, each on one phase.
The oven on its own phase.
If you have the knobs on the oven, all 3 phases plus neutral go into the oven which then splits the power as needed.
If these ovens are coupled with an induction cooker, the oven usually just passed the 2 phases along and communicates digitaly with the cooktop.
Power regulation is done by the cooktop electronics.
If it is a radiant cooker, power switching can be done either by the oven or the cooktop.
When you hook up 2 separate things, you just hook 2 phases to the cooker and 1 to the oven and all share one neutral and earth.
Have the setup of a separate induction cooker and oven mounted above each other back home and in my flat.
There are pre done upgrade wall plates with 5 triple wago connectors that I used at all 3 installs I've done.
More often than not you just have a cable coming out of the wall.
Screw the plate to the wall behind the oven.
Pull cable throug.
Put one cable in each WAGO terminal.
Then first mount the cooker.
2 phases. Neutral earth.
Then the oven.
1 phase. Check no phase is double loaded.
Neutral and earth is shared.
So the 3 phase terminals have 2 wires.
Neutral and earth have 3.
Cover on, done.
Check everything is running before screwing oven in place.
Oven and cooker installation have come a long way over the past dozen of years here...