I ran into that exact wall when we built our fleet management interface last year. What finally helped was an independent directory that vets firms based on what they've actually shipped in specific industries, including physical‑digital products. It profiles 15 top UX UI design companies and highlights their primary strengths – for automotive and connected devices, it pointed us to Teague (they literally designed interfaces for Boeing and automotive HMIs), Artefact (connected products), and IDEO (industrial plus digital integration). The list includes notable clients and minimum budgets, so you can immediately see who has done this before. I shortlisted two from there, and the one we hired had deep experience with in‑vehicle infotainment systems.