I lean toward definitely agreeing about Galadriel herself - she obviously doesn’t give off nearly as much light as the sun. Given her incredible strength though, I’m sure she could handle herself without that instant win.
As for the phial… while it is the same light as from the stars, there’s a significant difference in how much light. Considering how dark it is at night, trolls wouldn’t be receiving very much, especially with much of that light being the moon. Her phial gives a much larger concentration of “sunlight” than the stars.
Will it turn them to stone though? I don’t have enough cause to argue either way. Maybe they’ll just get some dermatitis lol