First of all, congrats! If it were me, I would probably sit down and list all of the companies I love and would be proud to represent that fit my niche. Maybe even a few that don’t fit just for fun and then just approach them. I do agree with trying to get them over to your Instagram and other socials first though. 100k on tiktok and 1k on insta would look funny but it is common. Build those up some and it’ll look good and just email companies you like and go from there. Trying to monetize will be more of a YouTube thing. Of course you can always do tiktok lives BUT they take such a massive cut it’s better to get donators to send it to your Venmo, cash app, etc.