Short burst of very high power output flashlight ?

The new phone cameras (mine is iPhone 11 Pro) are getting really good but I would love to be able to use a flash as a bounce flash off ceilings and walls to light a scene. Unfortunately you can't use a real flash as it won't sync with the phone. I thought perhaps a way to sidestep all the sync issues and be able to use with any phone or app would be an LED light with a short high lumen burst (at least 5 seconds to have a chance to compose and press the shutter.)

I got the idea watching a review of the NiteCore TUP. It has a button that you hold down for an instant 1000 lumens and as soon as you release it the light turns off. This is perfect for a flash action but I suspect I may need more than 1000 lumens to bounce off a ceiling and light the subject below in a similar way to a regular camera flash. I know the output of a regular camera flash will be insanely high and an LED won't match it lumen for lumen. But I think it could still work.

Any suggestions for products or how many lumens to look for welcome

Couldn't you use any light with tail activation? I mean you can just hold it in for as long as you want when your done release. And 1000 lumens should be plenty is my thinking. I have several 1000 lumen lights and bounced off the ceiling it's like day light.