I think a doily that's just a doily would be fine, people can decide for themselves whether to set a glass votive on it. Probably a lot of people do that, it seems safe enough. (Hopefully they wouldn't set the candle directly on it though.) But I'd be leery of advertising one specifically for that purpose, & the one that goes on the candlestick sounds scarier. (Maybe I'm not picturing it right?)
But warning or not, I wouldn't buy a product that isn't fire-proof or fire retardant to use with another product that's only real purpose is to be set on fire. :-)
maybe Google a few things like:
code of federal regulations candle accessory
ASTM standard fire safety
example- the ASTM cautionary labeling standard for candles requires a label warning consumers to keep candles away from things that can catch fire.