I personally would not consider superglue harmful enough to worry about plants seeping enough of it to affect the health of me eating the plant, and it’s not food grade. I’ve used it to fix cracked humidifier reservoirs in a greenhouse for example.

I would want to avoid something that leeches off into the water. That said, I am going to dilute it quite a lot since the stuff will be very concentrated. Super glue could be a little expensive for this though? I think coating the whole bed would take multiple small containers.

That being said, most epoxy resin dries food grade. I don’t think you’d have to search hard for a very well performing Resin with food grade search term swapped with dining surface or some frequent use that requires food grade.

I know very little about epoxy resin, but that is what I often see - but is it really basically the same stuff that is used to repair boats as people use for decorations? The safety data sheets for the components are always pretty rough, but they of course say nothing about the cured state.