I would presume not, but couldn’t find direct mentions.
Also, I like to play by my own or at most with friends at slap’s reach at arm’s reach, so I see no relevance for anti-cheats in my use-case. Plus, I see anti-cheat as DRM with more steps, and I care not for achievements for HL (if it even has any).
And so, I would like to know: should I be concerned about VAC if running the Steam version of HL through either/both?

Thanks in advance!