OK, so you don’t like to be on stage, you’re not alone; stage fright is common.
Perhaps you can be part of a group discussion, volunteer for a panel, MC somebody else, or mentor students at the university.
While these activities may not directly lead to sales they will give you a good standing in your community. For a lot of businesses that is worth more than any advertising you can buy.
As an extra bonus, when you start appearing and speaking you get bragging rights.
Mentored students at the university? It probably looks good on your LinkedIn profile! Introduced somebody far more famous than you at an event? Put it on your profile. The recognition is contagious.
If you still think public speaking is the most scary thing in the world, join an organisation like Toastmasters to help hone your skills and have somebody to practice on while you build up your courage.