Any recommended service or custom server to map all user's custom domains to their subdomains?
Example: sudo.lglg.me -> sudo.dev
You can achieve this in many way, after trying many ways, we finally decided to go with bunny..net as reverse proxy for managing all customer subdomain and vanity domain for customers. This is far by the easiest, cost effective and less complex and completely automated via API.
If you're someone from the future looking around for an easy and reliable way to handle custom domains, give https://approximated.app a try (I'm the founder). It's reliably serving hundreds of thousands of custom domains as of today, it's super easy to get integrated in your app in the same day, and it starts at $20/month with a 7 day free trial.