Maybe do it in 3 phases:

Phase 1: desktop app. Doesn’t even need browsing capability. More of a launchpad for all the apps. Easy discovery, key management, wallet. If proves useful and popular move to phase 2.

Phase 2: full browsing experience. Probably chromium? If for some reason this isn’t sufficient or proves very popular, move to phase 3.

Phase 3: full OS. No idea what this would look like or why you’d want that, something to consider 🤔