If you're interested in learning the kind of particular skills used, there's a whole subculture in computer security having to do with Capture the Flags (CTFs), for a rather broad concept of "flag".

https://microcorruption.com/ is a quite a good one to get started with. (Because embedded systems are smaller and do less, they are easier to reason about, which makes it easier to see vulnerabilities.)

See also: https://www.reddit.com/r/securityCTF/

More broadly, the (with-permission) attackers are known as "the Red Team", and the concept is used against computer networks as well as in literal war-games by the US government.

There are websites that let you practice. hackthebox.eu is really popular. And there is a bit of a test to even get access to that.

Wow! Thanks for this! I "signed up" and it looks very interesting so far

Take the OSCP course, it is relatively cheap for the value of the content and it is one of the few certs in security that is respected.

From your profile it looks like you work for a big company. Ping some people in security and find out who runs your "Red Team" (if you have one). Make friends with them.

we call it hacking forums/teams. main motivation is some idelogical/political belief tho.

imho try to hack yourself first

Speaking of "Hack Yourself First", this completely non-ideological (though somewhat commercial - it advertises the creator's Pluralsight course) website where you can learn and practice intro hacking skills:

https://hackyourselffirst.troyhunt.com/