OK, you already have a UV flashlight, even if it seems to be a quite old one (it says it is being sold for 20 years, I hope they updated the LEDs sind then…)
When you need more power to see more, Alonefire again could be the one for you.
FOr example: 60w 365nm UV-Taschenlampe ultraviolettes Schwarzlicht wiederauf ladbare tragbare Erz Geld Skorpion für Haustier Urin Detektor Harz Aushärtung sv53 - AliExpress 39 This light has 3 LEDs with 4 Chips each, so theoretical around 12x the amount of UV light as a normal one, although these chinese LEDs are less efficient.
Or if you want a smaller one - with just one 4 chip LED: SV003 LED-UV-Taschenlampe, 10 W, Skorpion, ultraviolettes Licht, Gelddetektor, Haustierflecken, Jagdmarker, Kontrollbrenner 18650 - AliExpress 39
64-Chip with battery and USB Charging: 120W 365nm UV Taschenlampe 6Licht Ultra Violet Schwarz Licht Tinte Trockner Geld Fluorescer Katze Hund Urin Tinea Erz geld Detektor SV116 - AliExpress 39
Or maybe even 94-chip LEDS with battery and USB Charging? 180w 365nm ultraviolette UV-Taschenlampe 9 Kern schwarzer Spiegel lila hell Holz UV-Haustier Urin Tinea Erz Tinte Trockner Fluorescer Detektor - AliExpress
Don’t pay attention to the claimed watts, that’s typical chinese marketing, more bigger = more better.
I don’t work for Alonefire, I just happen to have 3 lights from them here because they are cheap and I wanted to try some cheap lights out. And as far as my knowledge goes, the quality seems to be quite good.