Get google sheet, cursor.ai, excalidraw.
List all the pains your target users are having, and list the ideal benefits they would love (or features if they are techies).
Get a the top 3 pains and start drawing what it could look like from a solution perspective.
When satisfied, open cursor.ai and provide the excalidraw so it can get you a quick codebase. Use a simple tech stack that you either know or you can deploy easily. No fancy microservice for now.
Iterate until things work: login, registration, email verification, 3 features, etc.