my younger sister buys nail polish like that and I think its as accurate or the same stuff used in other LCD thermometer type devices.
in a European country which defines/suggests minimum/maximum safe temperatures for a workplace it might even be a valid piece of at least secondary evidence of somewhere too cold/hot to work in safely (e,g UK guidelines are 16 deg C minimum for offices and 13 deg C for warehouse/heavy industry/factory type place)
@AnnaGerber @saper is it not possible for your building services department to turn down the airco? I remember working in a govt building in the early 2000s (ironically for UK Environment Ministry!) on the 6th floor and there were many complaints if the airco was making the place way too cold, especially from older chaps (including many senior managers) as ventilator fans in the ceiling blasted cold air upon their bald heads! (some said "if this carries on, we will keep our hats on indoors" 😆 )
@saper @AnnaGerber actually one of our nursing homes has no easy way of regulating temperature other than the radiator valves in individual rooms (which means corridors, offices and everywhere else can be unbearably hot. Server/comms room has its own airco independent of everything else which is cooler doesn't have much space to work in (airco and multiple ventilator fans are noisy as well)