Household software is used in two completely different postures. Sitting down, planning, on a laptop. And standing in a store, in a driveway, in a hallway, on a phone. Neither is the real one, which is why a feature that only exists in one place is only half done.
The pull is always toward the web
Work starts on the web because it is faster to build there, and the mobile app is a separate codebase with its own idioms. Every single time, there is a moment where shipping the web half and doing mobile "next week" is the obviously reasonable call. Next week is where features go to become permanent asymmetries.
Share the middle, keep the edges thin
The way to make this affordable is to do the shared parts once: the calculations in a common library, the design tokens in one place, the data access in one API. Then each client is a thin layer of presentation, and building the second one is an afternoon rather than a project.
If it only works on the laptop, it does not work in the hallway — and the hallway is where the household actually is.