I know it depends on the site/app, but for a hobbyist, what is the biggest gotcha in a "got super popular over night" situation? If I look at the quotas and overages for low-end plans from the following providers, e.g., it's not obvious to me where the realistic bottlenecks are:
* Firebase Hosting with Firestore
* Cloudflare Workers Sites (using KV)
* Netlify (possibly w/ FaunaDB)