The technical product owner is not a role but it DESCRIBES a person in a Product Owner role with a technical background and who works on a technology product. And business-focused product owners are more towards the functional ASPECT. It is always good to have a product owner with technical knowledge, they can understand the product and can create a STRATEGY for successful delivery. Also, if the Product Owner has the technical background, they can understand the technical blockers or impediments and accordingly visualize the impact on the release. But technical knowledge is just good to have, there is no expectation that the product owner should have it as an essential skill. 

Also having a technical background doesn’t mean that they have to jump in the code or work around the architecture. In the case of business-focused product owner, they totally rely on the development team for all the technical DISCUSSION and decisions. This HELPS the team to become self-organized, even the Agile principle says “The best architectures, requirements, and designs emerge from self-organizing teams. Nowadays we have started noticing the openings for a technical product owner, wherein the organization needs Product Owners to understand the company’s technology at a deep level.