Camera advice needed for equipment update

Hi all! * I will take any and all advice! Willing to listen and learn, as I don’t know everything about the realm of cameras and what all can be done with them. I have previously shot for sports photographers, rodeo photographers, wedding and event photographers, but am wanting to branch out on my own! I just want to make sure that I can shoot quality photos and videos to be able to sell them with the equipment that I invest in! •

• Budget: $3,000 USD (or less)
• Country: USA
• Condition: Would consider either option, preferably new.
• Type of Camera: Mirrorless
• Intended use: Photography & Videography
• If photography; what style: portrait, sports (football, rodeo,baseball)
• If video what style: sports, events
• What features do you absolutely need: dual card slots
• What features would be nice to have: auto light adjustment, focus stability
• Portability: pretty portable and light enough to hold for long periods of time
• Cameras you're considering: Nikon Z6iii- for the quality of the camera and features it offers, Nikon Z8- upgraded features
• Cameras you already have: Nikon D40- older but still has great image quality. I know there will be many upgrades from my current camera, I have gotten to shoot some videos with my friends Nikon Z50ii, but want to make sure that I have many options with this purchase.
• Notes: I will take any and all advice! Willing to listen and learn, as I don’t know everything about the realm of cameras and what all can be done with them. I have previously shot for sports photographers, rodeo photographers, wedding and event photographers, but am wanting to branch out on my own! I just want to make sure that I can shoot quality photos and videos to be able to sell them with the equipment that I invest in!