Have a viral sports tiktok account with 500k followers — trying to get partnerships

Hi all! My buddy and I have a tiktok page that has over 500k followers and averages 60-100k views posting every other day. Some vids hitting over 1M recently. We have reached out to countless brands, mainly thru tiktok dm’s where they’ll tell us that they’ll send the info to their higher ups and get back to us if interested — or they’ll have us email the person that is in charge of their marketing

At first, we would dm all the companies that interested us — say “hey, we absolutely love your snacks. We were wondering if you were interested in a paid partnership”

Recently we’ve been trying in dm’s — “hey, we’d love to partner with you” just to any brand that we are interested in (drinks, snacks, apparel)

Does anybody have thoughts on what we could be doing differently that could be more effective? Or what has worked for them? It seems like there are many agencies out there but 99% of them are scams it seems. Do you know of any legit agencies that would work with an account our size?

Also, how much should we be charging a “flat rate” per video? This is all a brand new and unprecedented sort of market.