Just wanting to run this idea by others, but we're looking at making our place cards with coloured card stock to colour code our menu options and fit our colours (purple, blue, and green, all pastel card stock). Is that enough? As someone with different dietary needs and allergies myself, so it's something I worry about. The venue will should have the seating chart and list of meals in advance, but asked for something to tell them apart, like a ribbon on the chairs or something on place cards. I could do ribbon as well, but not sure if that's worth it as it will take much longer.
This is an example with the 3 colours in behind just to get an idea of what it will look like printed (I'm just using my own printer). I'd also do full names, but this is just a test. The frame is modified from a Freepik template and the font is Kecap Personal Use Italic, but I might change it.