DPC and TPA are very different. Most large traditional insurance companies now act as more of a TPA as purchasers/employer groups bear the financial risk for health care and use "insurance companies" to act as a TPA. Typically the TPA will have a strategy to health, quality, and financial management they bundle as a product. Wellness services are part of the product. You need to figure out how to become part of the wellness service strategy and demonstrate your value to a TPA. This could involve performance guarantees, risk based contracting etc. Happy to talk more to help you frame this as an offering/pitch to a TPA.