Decentralized ventilation units for larger rooms (old buildings)

Have you ever seen such a decentralized district heating exchanger - the boxes are huge, I wouldn't spoil my apartment with that.

As already written: I have a Bavarian ventilator in the laundry room. By the way, self-installed. I already know what it looks like.

Classic decentralized pendulum fans with heat recovery would be the pinnacle for me, because with those things you basically only see the grille. Choose a model with a flat grille and max. 10x10cm

The problem there is the noise level. Due to the constant switching of the fans, it is noticeably louder, from everything I've read.

That's the problem: the volume.
Due to the constant switching of the fans, it is noticeably louder, according to everything I have read.

Louder than what? At which level? Yes, they are louder. But not loud.

However, they are 4-6 times smaller and 3-4 times cheaper.

Significantly louder than what? At which level? Yes, they are louder. But not loud.

Significantly louder than Meltem and Bayernlüfter. And with much less power.

Significantly louder than Meltem and Bayernlüfter.
And with much less power.

I don’t understand. Which fans do you have and which fans are you comparing what to?

Let's take the "Meltem M-heat recovery II". It has a capacity of 10-100m³ per hour. At 50m³ per hour, it produces an interior noise level of 33.9db. Are there any swing fans that can keep up with that?