A more hidden champion is Ankersteine. I have one of their construction kits which is in my family probably since around 1885 and these kits are still produced today.
Lego has these, too, of course, but with Lego you at least have the benefit of being able to infinitely combine these parts to build stuff from them. Playmobil is "dumb" in that regard, you can't combine anything except in those ways in which it was specifically designed to be combined.
The real alternative to Lego in my opinion is Duplo, from the same manufacturer. They have no really small parts at all, so these are really good for outside play. But still infinitely combinable.
[1] https://www.playmobil.com/en-us/content/junior_themepage/jun...
Other than Playmobil and Lego I have not seen toy fischertechnik for years, but I occasionally recognize their non-toy fixings.
Fischer was the most prolific German inventor with 570 patents, who amongst other things invented the plastic wall plug.
https://www.fischertechnik.de/de-de/produkte/industrie-und-h...
There is a „toy“ section for children, but it is to learn about electricity or renewable energy, and I think the real customer of the page are not the depicted children, but the papa with an engineering degree.
https://www.playmobil.com/es-es/
https://www.playmobil.com/fr-fr/
and based on the dropdown at the bottom, quite a lot more countries