Bullet-resistant glass

If the key is next to the lock, you don't need to lock it either.

Aha, that just has nothing to do with what I wrote. And additionally, I consider your statement to be wrong.

The DIN EN 1627 rates the resistance time of RC1N, RC2N, and RC2 at 3 minutes equally. Only with RC4 are 10 minutes achieved by experienced perpetrators. However, the safest window is of no use if the installation is not carried out statically accordingly and this is also confirmed by the executing company. Therefore, do not settle for "RAL installation" or the like. That is only a recommendation. Insurances are also aware, especially in solid house construction, of the low strength classes of the masonry. Whoever really wants to secure themselves must therefore meet all 3 requirements. Everything else is just window sales marketing, especially in existing buildings. Here, hardly any structural engineer alone will want to confirm the sufficient strength of the wall.

Resistance times are one thing, the other is the tool used... Now the OP should express what his actual goal is.

The aforementioned RC correspond to the tools.

What kind of windows did you choose?

We stuck with the standard, so no certification, no special glazing, no lockable handles – nothing. There is also no fence/hedge, no alarm system, no guard dog or even weapons in the house. And it can easily happen that our front and terrace doors are wide open while we spend hours at the neighbor’s tap. However, we are also the type of people who would offer coffee and life advice to a caught burglar – "victim" after all. I just checked; in one of our tilt-and-turn windows there are a total of 9 mushroom head locks. Additionally, the area below the handle is reinforced with a steel plate and the handle itself is a so-called Secustik, meaning it is somewhat protected against manipulation from outside. And of course, I paid attention to proper anchoring during installation (albeit for other reasons). That (and the exterior lighting combined with the neighbors’ watchful eyes) has to be enough for the "feeling."

We have RC2 and lockable handles and a few other safety features, but especially very attentive neighbors (retirees). The latter are priceless and in my opinion the most effective since they also immediately and very directly address strangers ))

Regarding the protection classes: There are nice videos from glass manufacturers showing how burglars try to break a window with paving stones and then hit it with a huge hammer, nothing happens. You can go as far as bulletproof glass. Only I think I remember that from the insurance’s point of view such measures have to be appropriate. If I remember correctly, an insurance will not replace such a damaged, super expensive RC4/5 pane if you install it just for fun or to protect your surprise egg collection or porcelain figures. It’s been too long since I dealt with it to back it up with sources. Maybe someone here knows more about it.

And last but not least: Like with a car with burglary-resistant glazing all around, in an emergency it can hinder rescuers from helping you. The fire department will find access with their heavy equipment, even if perhaps somewhat delayed. Whether first responders from the neighborhood will get in during an emergency (fire etc.) I’m not sure. Looking at the windows and doors, probably not.