That is in principle correct, but since OP is using a throwaway and a know anonymous domain service. As long as he burns bridges after himself (eg. not making it into a adressable business later), there is not individual to deliver a letter to.
Might work for a while, but a dangerous game to play...
It’s a bit more nuanced, you don’t need a Impressum for purely personal websites without financial background. Evaluating a business idea would probably count as financial motive though, even if it isn’t currently monetized.
The economics don't matter, everything that is regularly updated or offers a service needs an Impressum. The exception for "purely personal or familial" use clearly doesn't apply here because a service is being provided actively.
It mandates a Impressum for „ geschäftsmäßige, in der Regel gegen Entgelt angebotene Telemedien“. If it’s not geschäftsmäßig (Business-Like?), you don’t need an Impressum. If you do it for free without any intention to make money now or later, it’s not geschäftsmäßig.
If I have a blog that I update regularly but don’t have any ads from or take donations for, I don’t need an Impressum.
Impressumspflicht only applies for commercial interests. If you are a company informing or even selling something, if you are an influencer making money of yourself, or even if you just have ads on your Pokemon-fanpage, then it counts as commercial interest.
But I don't see any direct monetary value on this site at the moment. There is not even a reputation-gain, as there is no personal information. So Impressumspflicht would not apply.
Might work for a while, but a dangerous game to play...