Rotary phones have a cult following, but their functionality is outdated. A kit that lets users upgrade them to work with modern networks could appeal to collectors.
The kit would include components like ESP32-S3 modules and clear instructions for installation.
Collectors and hobbyists would pay for the nostalgia and uniqueness.
Launch with a basic kit for rotary phones, then expand to other vintage devices.
Risk: Small niche market may limit growth.