EDIT: I believe I found the answer, it's something turned by this: https://ctatools.com/products/5065
Found some trash on the street that i'd like to take apart, but this screw is in my way.
It's like a hex bolt, but with 5 sides, and rounded (a bit like flower petals).
Here's another picture from the top:
I tried turning it with various tools (hard to get pliars in unfortunately), no success so far. The material is very soft, which doesn't help..
That is some variety or another of a “torx star” head. They vary in size and are listed as TS-10, TS-15, etc. your best bet would be searching torx star and buying a set of bits to try out various sizes.
And it's an inverted torx (with 5 points) as usually the screw driver is male and the screw head is female - I think that's the right nomanclature.
https://germantoolblog.com/2017/06/01/torx-and-its-many-variations/
I think I found it, it's this kind: https://ctatools.com/products/5065x12