Single room ventilation and cooling

I am considering installing a bit more living comfort in my home.

The plumber I trust is fully booked, so I would like to hear your experiences before I let a third party talk me into something completely unsuitable.

We have a new build from 2020, without a ventilation system. (You learn for the next house, but that should not be the topic here)

The only room where we have comfort problems is the bedroom, size 15m2 (so increased condensation on the window in the cold months, high humidity, feeling of stuffy air - (still) no mold).
Here we would like to retrofit a ventilation system to better regulate the humidity.

In the summer months, additional cooling would be desired. The performance does not need to go down to 18 degrees, but at least more pleasant temperatures than last night (25°).

Which systems would be suitable for this?
That is, ventilation/humidity/cooling.
Or would this be several components?

And do you possibly have manufacturer/device recommendations?
Noise level is of course also important, as it is used in the bedroom...

A ventilation system does not cool. An air conditioner does not provide fresh air (oxygen). So you need both (exceptions prove the rule).

Maybe also monitor CO2 in the bedroom.

In the bedroom, however, I would rather advise against the oscillating fans. When the fan runs on a low setting, the gentle noise is not a problem. However, it changes direction every minute, and the stopping and starting is disturbing, especially when falling asleep. That's why we set ours to an 8-hour pause at night. I would rather opt for a simple fan that just blows outside air into the bedroom. Regarding the temperature, I would first look for optimization options so that the temperature does not rise too high. If shading during the day and ventilating in the evening is not enough, you can hardly avoid an air conditioner.

The only room where we have problems with comfort is the bedroom, size 15m2 (so increased condensation formation on the window in the cold months, high humidity, feeling of stuffy air - (still) no mold).

Let me guess. Heating completely turned off in the room in winter, doors to the bedroom closed. ==> User error. In new buildings, condensation formation on the window is solely a user error. ==> Proper ventilation and keep doors open. Set temperature to normal - you can also sleep like that.

In the summer months, additional cooling would be desirable. The capacity does not have to be lowered to 18 degrees, but at least more pleasant temperatures than last night (25°).

What kind of external sun protection do you have on the house? Yesterday we had 32 degrees outside and about 23 degrees inside in the evening. At night, thanks to open windows, below 20 degrees. Roller shutters on the sunny side were down. Otherwise, I agree with the others. Fresh air = ventilation and cool air = air conditioning. P.S. Good decentralized fans are quiet enough for me at night as well. I have one installed in my own bedroom. The oscillating fans can also be set as desired (on/off/supply air/exhaust air/oscillation mode). So it would also be good to set to supply air on a summer night. However, retrofitting is a relatively high effort with core drilling and possibly laying electrical wiring.

I also have a supply air fan with heat recovery in the bedroom. We use it exclusively in supply air mode. Energetically suboptimal, but more comfortable at night.