Hi, @BeWater
That’s a great question. Thanks for posting!
If you want influencer’s to be able to order the product from you, but not the general public, simply not adding this product to your live collections will prevent that. This way, the product is technically available in your online store, however only via direct link. Once you create this product in your Shopify admin, you will see the URL at the bottom of the product page and be able to provide that to influencers for purchase.
I hope that helps! In the meantime, are you using an affiliate program for the influencers you work with? If not, I recommend checking out Shopify Collabs. It’s a great way to connect and expand your influencer outreach.