The decision
Treat headless as an investment with explicit expected returns and operating costs.
Separate the storefront when theme constraints materially limit product experience, content, market variation, performance, or integration, and when the expected value exceeds the added operating cost.
What it changes
Shopify still runs commerce; your team now owns the presentation system.
The independent frontend gains control but adds hosting, caching, releases, monitoring, preview, incident response, and specialist maintenance. Those costs continue after launch.
US-market variables
Consider scale, content velocity, and organizational ownership.
Payments and checkout are often straightforward in the US, but merchandising, retail integrations, subscriptions, experimentation, and global market needs can make the surrounding system complex.
The reverse signal
Fix the theme and app stack before replacing the frontend.
If performance problems come from oversized media, unmanaged scripts, duplicated apps, or poor content operations, address those first. A new frontend can reproduce the same dysfunction at greater cost.