> I personally am not fond of eating hot degraded PTFE

If this is a problem, you should buy a new printer that actually keeps the filament conduits away from the hotend. This is a health hazard regardless of food safety - decomposed PTFE is nasty stuff to breathe in.

> Or the trace remains of charred ASA/ABS I printed last week through the same nozzle...

Fair enough, but I would also say that you should be purging old filament anyways before starting a new one. My slicer does this by default.

> Or in fact any of the various coatings of the heated bed or leftover trace amounts of previous prints...

These days, heated beds are covered in PEI. That's food-safe too.

I think your take is a little panicky and not supported by the evidence. It is perfectly fine to print single-use food stuff out of PLA, especially if you just have a roll or two of the pure (undyed) stuff around. You're much more likely to get sick from the food itself than the plastic it touched for a little while, and PLA is relatively biodegradable compared to most other plastic foodware.

There's also the issue of lead in the brass nozzle, so you'd probably want to switch to a safer material there.

Also lead from brass nozzles. I think the risks are overblown, but recommending anything that is not recognized as food-safe for use with food is a liability, better safe than sorry, as they say.

There are food safe coatings though, these deal with the problem by making your 3D print not in contact with food.

The main solution I've heard is to just encapsulate the whole thing in foodsafe epoxy. Then it doesn't matter as much what the inner material in so long as you monitor for damage.