Design flooring as a parquet alternative - purchase recommendation, manufacturer

I am now considering whether we should additionally seal the floor (for durability).

I would actually pay more as long as you also get better quality. Friends have installed Modular One and are satisfied. However, there is one or two joints that do not close completely sustainably..

I think everyone should decide that for themselves...;).

Well, everyone has that freedom. But you want a robust floor because of the children. Unfortunately, the same floor is so robust that it will exist in the ocean and thus in the environment and in the bodies of these children for another 200 years. You (unfortunately) can't just settle environmental issues with yourself.

I recommend linoleum. It is durable, reasonably environmentally friendly, comfortable on bare feet, and nice. It's a pity that it has somewhat gone out of fashion. But that's often the case with "simple" stuff. People prefer only developed things over proven ones.
I myself have engineered hardwood flooring with underfloor heating and would certainly have liked linoleum as well. Sometimes I regret it a little.

Second or third grade parquet isn't that expensive. Engineered hardwood can also be repaired with hot wax. It's advantageous if you don't choose the top quality sorting without knots, but rather something ordinary.

I would really advise you to reconsider and carefully look at what kind of floor you choose. Of course, it is always quite expensive, but the floor really lies there for generations (and with a lot of plastic unfortunately for generations in the environment) and definitely largely determines the atmosphere of the rooms.

I have never once thought about a "design floor" (the word alone is already a euphemism): oh, how beautiful! The floor really dresses the room nicely. Or something like that. The maximum feeling I get from such a design floor is: doesn't bother me. That would be too little for my own home.

Correct, parquet manufacturers save at every corner and every end. Please understand that I am not willing to pay over 100 €/m2 for a plank that is even remotely as large as what you could get as a design floor.

I do not accept that regarding the price; I am currently installing a basement room with engineered parquet floating. The small parquet manufacturer Berg&Berg has caught my attention, they mostly have country house planks measuring 239x20 cm, so really large! Street price for oak, brushed, filled, smoked, and oiled is around 100 euros/m2.

I have now bought them in second choice for just 35 euros/m2. And there are really only tiny flaws that I have been able to find so far. As a precaution, I simply bought 5% more than actually needed, so I can practically make all the "little problems" disappear by trimming these planks accordingly or just leaving them out. The dealer also has simpler (that is, only oiled) Berg&Berg planks second choice starting at 20 euros. Something like that can compete with any vinyl floor - better real wood than plastic imitation...

Well, everyone has freedom. But you want a robust floor because of the children. The same floor is then unfortunately so robust that it will exist in the ocean and thus in the environment and in the bodies of these children for another 200 years. You (unfortunately) can't just make up with the environment on your own.

Have you looked at Ecuran as a base for Pureline?
Sounds to me not so different from linoleum, plant oil and solids processed into a plastic.
Both last a long time, both are disposed of via residual waste, meaning they go to thermal recycling.
Ah, I just see that linoleum is even compostable (but it takes a very long time, so there are hardly any facilities that accept it).
Still sounds quite environmentally friendly!

The environment is very important to me, I have dealt with the topic extensively and then decided.
Sure, pure wood is even better for the environment, but it costs twice as much, quickly looks stained in the kitchen, and significantly reduces the efficiency of underfloor heating.

I am happy to be corrected, but the Wimeo Purline does not exist in the long plank format, only as sheet goods or short planks, right?

The Blue Angel does by no means certify the complete harmlessness of a product.

Nothing can certify you complete harmlessness. The direction is right, and that already counts for something.