What it changes for you
A model that can hold a million tokens of context reads more of your site in one go, so the shallow, keyword-shaped page matters less and the substantive, internally consistent one matters more. File and image input means your documentation PDFs, architecture diagrams and pricing tables are now readable evidence, not dead weight. If your product claims are only defensible in a sales deck and contradicted by your docs, a model working at this context depth will notice.
Where buyers meet this model
Buyers meet GPT-5.6 Sol in two places: inside OpenAI's consumer and business assistant products, where it serves the highest tier of requests, and directly through the API when their own vendors build on it. In practice, a buyer researching your category is likely to be reading an answer composed by a model in this family, whether or not they know which one.