A website remains the primary discovery channel for a trade business — it's what shows up in search and Google Maps. A branded app serves a different purpose: keeping existing customers engaged after that first job, with booking tools, push notifications for availability, and job history access.
Businesses with recurring service relationships — maintenance contracts, regular callouts, subscription-style servicing — see the clearest return from an app, because it reduces friction on repeat bookings.
For most sole-trader and small trade businesses, the website and local SEO foundation should come first; an app becomes worthwhile once repeat-customer volume justifies the investment.