"Proven" is a tough label to apply to virtually any ingredient/product. There are favorable/unfavorable studies and anecdotal accounts for just about every supplement.
That said, if you want a product from a top brand that was formulated to increase NO/blood-flow and overall performance using ingredients backed by actual human data, you won't get much better than
Olympus Labs Conqu3r Unleashed Stim-Free. It's on sale for 50% off for a limited time; just add to cart.
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https://olympus-labs.com/product/conqu3r-stim-free/
Read the write up to see how the ingredients were chosen. Some snippets:
L-Citrulline
Nitrosigine
Agmatine
Creatinol-O-Posphate
ElevATP
And that's not even including the Focus and Adaptogen Matrices. As you can see, as far as "proven" ingredients go, Conqu3r Unleashed is top-notch, and at $23.99, nothing comes close.