Ive done it...but we used a bilge pump to help prime the lines while cranking...once its going it will take water in by itself

No

I've run my Bravos numerous times in a plastic 55 gallon drum laying longwise on the ground with a slit cut in it to fit the drive in and just the water hose filling the drum, no muffs.
It always pumps water.
I do it just to ensure the impellers are indeed drawing water.

Grand Dad always said first lair doesn't stand a chance

Clearly the video shows otherwise, but that does not sway you. I have personally run an engine on a stand with the intake hose from the Bravo 1 pump stuck into a large container of water below the pump level. Not only did does it draw up the water quickly it does so in copious amounts. It pumps out water at idle faster than my garden hose could fill the container. Pump is fine. The vane pump by design will draw water up to it.

I ran a kohler generator about 5 hours this week with the pump sucking out of a 55 gallon drum.
And then there’s this kit for winterizing

Everyone better return there outdrive earmuffs…clearly they won’t work

I don't often flush my boat. but when I do, I make it suck water out a hose in a dark alley.

https://southpark.cc.com/video-clips...-out-of-a-hose

I need to call this one out too, having 496's, when those brass end plates have groves in them from wear, they don't prime because the clearances don't allow "suction"
this is why the rebuild kits feature new end plates and why the Hardin stainless pumps are so much better
That said I've personally seen a 496 with bravo 3 run on the trailer in a 55 gallon drum of water, it's the exact same scenario as the boat sitting in the water, this is also why they say not to run an engine on the muffs faster than idle speed, because the pump will suck the water faster than the hose can supply it

I never had any luck using that on my 496. I had to buy a bilge pump to suck from a bucket, to pump into the ears. After that no issues.

Went to sea strainer and had hose connection feed in. One of the best investments I did to the boat.