Buy a wood stove quickly now?

Yes, yes. At least that's what the providers claim. You can click on "fast delivery" on some marketplaces. There are still a few...

It's not enough that you have an oven. It also needs to be installed and approved. You'll certainly be waiting weeks for that.
At this point, I'm also skeptical whether a wood stove is really the best solution. More sensible for a multi-day blackout would probably be a small generator that continues to supply the house. At least you could also use that to keep the beer cold at the next festival.

Otherwise... yes, panic is currently being spread in the news. Bad news are good news and a long blackout simply sells better than rolling outages where you lose power for about 2 hours at a time.

If the power is out for 2 days or longer.. then you can expect other problems.

In winter, it will first and foremost get cold. What could be more important than that?

It's not enough that you have an oven. It also has to be installed and inspected. You'll probably wait weeks for that.

Cute - typically German. When freezing temperatures are threatening, I couldn't care less about an inspection... We're talking about an emergency here.

You still have to install it correctly. Otherwise, you'll just smoke out your living room and then have to air out the remaining available heat. ;)
We once had a heating failure in November in a block of flats from around 1980 with zero insulation. It was a bit chilly after 2 days but still well above ten degrees. In a modern house, it will take far more than 2 days of power outage before you face freezing temperatures. The screed alone keeps heating for a day.

Therefore, we are considering setting up a small wood stove.

Yes, yes. At least that's what the sellers claim. On some marketplaces you can even select "fast delivery." There are still a few...

What do you understand by small wood stove? For us, it had to be a certified one. They are not that cheap then. I assume it must be room air independent. Do you have controlled residential ventilation?

Cute – typically German. When freezing temperatures threaten, I really don't care about an inspection... We're talking here about a kind of emergency.

Well, then the place fills with smoke or carbon monoxide spreads odorlessly...

I can't give you any advice. Do you have a wood source?

From what I read, the train for this winter has already left the station anyway. But the next winter is supposed to be even worse. And as some have already said, in insulated buildings, heat retention is not the issue for a few days, but power generation and drinking water supply. I myself am still not quite sure whether I should do something about it.