As a fellow young millennial doing red team security stuff professionally, XP is different from the others for a few reasons.
The first is that XP has a tendency to, by default, open a lot of forward facing holes and services that to my knowledge most other "old timey" OSes don't. I'm not familiar with riscos or amigaos, but I do know old versions of OS X ship with basically no attack surface, while XP (IIRC) will enable SMB and guest access automatically.
The second is that unlike those other OSes, XP was and is very widely used, and there are exploits which target XP and a range of other commonly used Windows machines. Unlike basically any other niche retro hardware, Windows is both 1) pervasively networked and 2) very widely attacked, and lacks basically any modern mitigation for exploits, so a simple buffer overflow in a networked service can easily become a RCE.
The first is that XP has a tendency to, by default, open a lot of forward facing holes and services that to my knowledge most other "old timey" OSes don't. I'm not familiar with riscos or amigaos, but I do know old versions of OS X ship with basically no attack surface, while XP (IIRC) will enable SMB and guest access automatically.
The second is that unlike those other OSes, XP was and is very widely used, and there are exploits which target XP and a range of other commonly used Windows machines. Unlike basically any other niche retro hardware, Windows is both 1) pervasively networked and 2) very widely attacked, and lacks basically any modern mitigation for exploits, so a simple buffer overflow in a networked service can easily become a RCE.