I’m not entirely sure about food hygiene regulations being applicable… someone with more knowledge would have to speak to it but isn’t there an aspect of whether you’re catering to somewhat of a public crowd? If you invite all your friends over to watch the game and grill steaks in the back yard, are the food cops out there trying to shut you down when you inevitably break one of their rules? (IOW when do food regs apply vs not?) So how public is this funeral going to be?
I think the form of the body is what’s important in any legalities.
The remains of a modern cremation are pretty much just ground up bone fragments that have been heated high enough to kill any kind of pathogen imaginable. You’d essentially be handing out powdery spoonful’s of your friends pasteurized bone dust… which probably wouldn’t even dissolve but remain as a tasteless grit in the bottom of the cup. Unless he had some heavy metal contamination in his body or other substance that wouldn’t be degraded or driven off by extreme heat, I don’t know what would be in that dust of concern. And if he was full of some deadly metal that got bound up in his bones and remained in a toxic form through the process, you’d only be getting a tiny fraction of it, whereas the entire amount he had in his body wasn’t enough to kill him (assuming he died of some other natural cause)…
AFAIK scattering ashes/remains is commonplace pretty much everywhere; I’ve never heard of it being illegal. If it is, I’ve never seen it enforced. The funeral home (or whoever does the cremation) hands you a container of dust, and you’re free to do with it what you please. It’s pretty much inert and harmless.