Start by doing just what you've already said.
Do reviews, be different, be interesting, CREATE the interest, then companies will FIND YOU.
Sorry, but it doesn't work the other way unless you can get hooked up with a hungry start up company. Good luck with that in today's environment!
Can you imagine all the people, like yourself, asking these companies, daily, for free crap? I'm pretty sure they are on the long list of things they ignore!
OK, I like Heather's Heavenly vapes NET juice line, I've bought several hundreds of dollars of their juice, they've yet to ask me for a review for freebies!
So do what you think you want to do, get established, get a following and they will come to you. Sorry, but it's not the other way around.
Also, for the record, there are VERY few of these "reviewers" that I even half trust! I believe most of them have been bought and paid for before they even start the review! I've found a large part of what they claim as "excellent" is pure crap most of the time!