Wondrous item, common
Evokers and alchemists alike teach apprentices to make Glowing Dust as their first enchanted item. The recipe calls for the light cantrip, 25gp worth of quartz dust, something bioluminescent (usually glowing fungus, glowing lichen, or dried jellyfish), and a week to work. Once complete, you have a bag of faintly-glowing dust, most useful for sealing in jars and using as fairy lights. If the bioluminescent ingredient has a strong color, the dust will also glow in that color, otherwise it tends to glow white.
A pinch (about a teaspoon full) of Glowing Dust sprinkled over a 5 foot square causes the area to glow with dim light, enough to read by, but just barely. When blown or thrown into an adjacent 5 foot square, a pinch of dust will stick to creatures and objects, causing them to glow and negate the effects of invisibility. A Dexterity saving throw DC 12 will allow a creature in the area to avoid the dust, but they need to know about Glowing Dust (GM's call here). A bag of Glowing Dust contains 10 pinches.
When opened, a bag of Glowing Dust sheds bright light in a 1 foot radius and dim light for a further 1 foot per pinch of dust remaining in the bag, so a new bag with 10 pinches will shed bright light in a 10 foot radius and dim light for a further 10 feet. Once coated, removing the dust proves problematic. Like glitter, it gets everywhere. The glow doesn't fade so it can be swept up and reused, but it will eventually scatter and dilute in plain dust, only faintly visible in total darkness.
Creative users may wish to dump the entire bag out to cover a larger area. This will work, but less efficiently than expected. The maximum dispersion of a full bag of Glowing Dust under ideal conditions (a controlled gust of wind spell or similar) covers a 15 foot cone (six 5 foot squares). The heaviness of the dust causes it to sink too quickly to cover anything further without moving closer.
The Crystal Beaker sells bags of Glowing Dust for the lowest price in Fellport: 60gp per bag. Higher end shops sell bags for 100-120 gp or sometimes more, especially around the midwinter celebration of Lightnight (Nocte Luminum). On the longest night of the year, the city's residents spread light through the streets at midnight using candles, torches, and magic, calling the sun back from his seclusion below the horizon. Nobody really believes they actually call the sun back with lights or that good triumphs over darkness in that moment, but the ritual and spectacle unites the populace in the darkest time of year, spreads hope, and fosters community.