Tandoor definitely has a self-hosted path, including SSO integrations. It has a fair API that I’ve used to link it to nutrition data at USDA and my grocery store for prices. I suspect I could use the API to transfer a shopping list to the grocery store’s ordering system, but I don’t like the pickup or delivery systems. I’ve been pretty happy with tandoor’s import-from-web results, although the ingredient amounts often need some editing.