Do household ovens ventilate heat to the outdoors?

I've never seen one that vents to outside, and I've used kitchens in several countries.

In many places we need to heat our houses for quite a few months each year, and the waste heat from cooking is very welcome. I try to avoid using my oven in summer, choosing other things to eat instead.

Note that modern ovens are designed to be well sealed and well insulated, but many have a fan to cool the space in which the oven is installed; that's the source of warm air into the room with the door shut.

You can minimise the heat produced (i.e. the electricity used by both the oven and the air conditioning) by opening the door as little as possible, and by only preheating if you really need to. A well-insulated oven can be turned off a few minutes early for many dishes as it will retain enough heat to carry on cooking. In other words - cook as efficiently as possible. The benefit of this is greater if you're using air conditioning.

So it's not directly fighting the air-con in summer, my usual trick is …

Oven on, kitchen window open, kitchen door shut.
If you have an extractor hood that vents outdoors, that's going to help the job the open window is doing too.

After cooking, oven off - mine has fans that vent into the room, separate from the ones circulating the heat internally. They keep going long after the oven is switched off. That's lovely in winter but not so much fun in summer.
No matter how it achieves this, or whether you open the oven door to get the heat out faster, the laws of physics say that sooner or later, all the 'extra' heat in the oven will make it into your kitchen. There's not a thing you can do about that.

Leave window open [& extractor on, if applicable] & kitchen door shut until equilibrium is reached between indoors & outdoors, when oven is almost cold.

Close window, open kitchen door, let the air-con do its job once more.

It's imperfect, but until someone designs a cooker that will vent directly to the outside, in summer only, then it's the best you can do.

Depending on your architecture, it wouldn't be impossible to mount an extractor directly behind the oven, vented to the outside - though as I've never seen this done anywhere, I'm guessing grease build-up would make it either unsafe or just require so frequent strip/clean procedures that no-one considers it worth the effort. Link to local UK supplier of kitchen vent systems. Commercial kitchens have massive extractor hoods over the range area [which get cleaned every few months] but they're really to vent steam & grease, not to cool the room. Temperatures near commercial ranges in kitchens reach two degrees short of "Why on earth would anyone want to do this for a living?" even in winter.

In order for the heat of the oven to be purposefully ventilated somewhere else, there would have to be not only a fan, but a back door in the oven and some way to trigger the opening of the door and turning the fan on and off.

There are no back doors in ovens.

There are some ovens that vent outside, but these are the exception. Assuming we're talking a typical North American oven, check one of your rear burners; the oven is typically vented through there. For induction or radiant cooktops, there's usually a vent above the rear elements.

Obviously there's no easy way around this, but if you were feeling inventive you could probably rig up some insulated flexible metal tubing (i.e. dryer vent hose) to pipe the heat out a window or range hood vent while you're cooking something for an extended period.

I have a swanky Viking oven that, when it decides to light and do some work, does exhaust heat to the outside via some interior fan. It is not the same fan as it has over the cooktop where you can see it sucking up smoke and cat hair. You can hear the interior fan go on about 5 min after the oven has been shut off.

So it is possible.

I've never heard of an oven being vented to the outside. So, unless you have an exhaust fan that is vented to the outside, you're pretty much stuck with the heat.

Note, though, that the oven will gradually cool down after the energy source is cut off. The entire amount of residual heat will not dissipate nearly as quickly into your house as long as you keep the oven door closed.

No ovens are designed to ventilate outside. I actually tried making mini oven with vent connected to window but it not only failed to contain heat but also heated my room anyways.