As per title. I very, very rarely drink, and I generally just want to buy a single of something for a rare treat, however most beers/ciders/etc are sold in multipacks.
The pricing on the shelf is usually per-pack only, yet sometimes I see random products with single cans/bottles missing, and sometimes random products will have a little section of unpackaged singles, despite not having a separate price showing.
Is it generally OK to split an unopened 4- or 6-pack, or is that as weird and inappropriate as doing the equivalent in a supermarket? What even are the rules around this?
That notice is not a legal restriction, nor a rule to stop stores from breaking up multi-packs. What it's there for is to alert buyers and cashiers that the barcode printed on each unit contains the product code for the multi-pack. If stores want to sell individual units, they just have to re-label them, or at least not scan the barcode.
The store in which I used to work sells individual bottles of beer, or build-your-own 6-packs. The liquor department manager just puts a slash through the barcodes with a black marker, so they won't scan on the registers.