“Alcohol is a mild poison” has been a house rule within my extended roleplaying circles for a long time. It fits well into almost any setting or metaphysics, and allows you to do interesting things with intoxication.
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...... it actually is though? its even defined as such in medical texts I've read.
Oh yes, although with roleplaying setting metaphysics, it's probably good to define this to be true if you're using it in your game. (To make sure it interacts with the rules correctly and has the right keywords etc etc.)
For example if you cast "detect poison" do you detect bottles of alcohol, or a hidden wine cellar, etc etc. If your DM has never considered whether or not alcohol is a poison it probably wouldn't occur to them to mention it, but if they have then they might!
I think I'd go for intent mattering for detect spells, but having it still work with healing.
I like that kind of thing in a lot of settings, especially more philosophical or metaphorical settings.
DnD always feels to me like it's a world where the metaphysics are defined by the players having an hour long argument at the table about "what RAW says", while people look up rules in books. Back in my 3.5 days, someone would manage to find a ruling in an obscure 3rd party book, in 4th edition, you'd find some hard definition in the source material. In 5th edition, someone will find a tweet from Crawford, and the table will agree it's stupid and decide the opposite is always true.
For my experiences in D&D, the question of "whether x counts as y" is a definition that sticks to the universe itself - there aren't many examples of metaphysics in D&D where the answer varies by intent. (I'm sure there are some though!)
Caveat: As with everything I say about D&D rules and definitions, this is not advice, just how I think of things, and the objective correct answer is always "whatever works at your table."