If you intend to keep majority stake in the startup (business vertical, in your terms), another alternative could be to keep the technical IP as your own proper

If you intend to keep majority stake in the startup (business vertical, in your terms), another alternative could be to keep the technical IP as your own property that you give usage rights to the startup (for free or for a fee). This would just be a simple contract and no need for setting up a company. If you end up taking outside money at some point in the future, you then have an option of packaging the IP with the startup (for a higher valuation that includes the IP) or just the business alone without the IP (for a lower valuation). You can decide on the separate company for the IP at that point in time instead of a premature optimization now. ps: I am in the same boat and I had the same question and decided to test the business vertical's viability instead of setting up intricate multi-company structures.