Construction costs are currently skyrocketing

Over 600 watt inverters are currently not considered balcony power plants, unless you do not live in Germany. In countries like Austria or the Netherlands, different regulations apply.

I have a vague memory that (not every) 800 watt inverter can also be throttled down to 600 output power

But who is supposed to check that...
If Aman simply states 600 watts inverter and has 800 watts?

There are few of them, but a few people can make your life really, really difficult once they have you in their sights...

These include:
The tax office. Your boss. Your (spouse) partner. And your network provider...

Unfortunately, there is a misunderstanding. There is no fundamental right to an electricity connection as long as the connection does not comply with the TAB. That means, if you get "caught," you may have to prove in detail with an expert, etc., that you have not violated and are not violating the TAB.

Only then will your connection be restored.

I once knew someone who was subjected to an audit by the tax office.
During the 2 years, he had not just once put the noose over the beam and stood on a stool... nobody needs that...

Especially not because of lousy 200 watts, which you can hardly use anyway.

You also have to register the balcony power plant in the market master data register and with your grid operator. You also have to provide the types. Of course, you can lie ... well. I just did that in November, it's not a big deal. And in general, I also think it's useful to know where and how many photovoltaic systems are installed. Because that will now increase rapidly and then the data will already be relevant for grid expansion planning. Because surpluses from balcony power plants also go into the general grid.

Does that actually make sense? There are now balcony power plants

These are two completely different use cases. Balcony power plants are a supplement for the household's base load. Since you do not receive a feed-in tariff, it also makes relatively little sense to dimension the balcony power plant particularly large. However, you have almost complete self-consumption. Something completely different are the roof systems. Here, the photovoltaic system more or less pays off through the feed-in tariff and then pays off through self-consumption. Here, you are also able to operate something larger, e.g. hot water through a heat pump, electric car,...