When people say a bad OS can fuck up /dev/urandom what do they mean by that?
Additional context needed to answer this question. But you probably read about /dev/urandom on Mac OS or BSD version which released few decade ago.
I think i am being ultra paranoid here.
So if i want to generate a strong random seed it doesn't depend on say hardware?
I mean if i have old PC will it generate less random seed compared to new gen PC?
If i use electrum on linux vs windows which is more better to generate random seed?
There should be no noticeable difference in terms of security. Although it's different case if you believe certain hardware/OS has backdoor to reduce the entropy.