Does a floating floor feel hollow?

On a cheap underlayment, yes. On a specified pad over a flat floor, it should feel quiet and even. If it sounds like a stage, the assembly is wrong.

Method · installation

Floating engineered hardwood

A click-engineered floor that rides on underlayment when the mill requires it.

Engineered click systems over the specified underlayment, with transitions and stair nosings detailed so the floor does not read as laminate.

Underlayment
The one in the mill packet. Thickness, density, and vapour control are a spec, not a preference.
Expansion
Floating floors move as a sheet. Doorways and long runs need breaks. Ignore that and the floor peaks.
Stair and vent details
Nosings and flush vents have to be designed for a floating thickness, not borrowed from a 3/4-inch solid job.

Mills that require floating, some retrofit rooms, and sites where glue-down is not warranted.

As a way to hide a bad subfloor. Waves still telegraph. Cheap click plank is not a Green Hardwood product.