Oh yeah definitely don't try this unless you have fiber and your ISP isn't too twitchy.
My suggestion is mainly for static site hosting since the Pi only needs to update the cloudflare cache when you make changes, and it should be able to handle a small db and few background services if you need them.
- Don't host anything media-heavy (e.g. video streaming)
- Make sure you have reasonable upload speeds (probably 10+ Mbps min)
- Even behind Cloudflare, make sure you're comfortable with the security profile of what you're putting on the public internet
The min upload speed is mostly about making sure random internet users (or bots) don't saturate your home internet link.