General-purpose script managers like Tampermonkey can't optimize for every workflow. A focused extension could handle authentication, data extraction, or UI tweaks for a single service.
Build a Chrome extension that solves one workflow problem extremely well, with a clean UI and pre-configured settings.
Freelancers or small businesses would pay to save hours per week on repetitive tasks in tools they use daily.
Start with a minimally viable version that automates one common task, then expand based on user feedback.
The biggest risk is picking too niche a workflow with insufficient demand.