Tiktok video

Can I add another video to promote my product at the end of every tiktok video I post? So the first half of the videos on my account will be totally different, but then the other half will be the same for all the videos, that is, a promotion of the product I'm promoting. Is there a chance of a shadowban?

No, it's very unlikely you'll be shadow banned as I have seen TikTok accounts promoting their products in every video, and they still get pushed to the ForYou page. However, I would recommend you try TikTok ads as they are more efficient in promoting products.