Based on the page it looks like you can install Cloudflare's CLI and then run `cloudflared tunnel --url http://localhost:3000`, and you'll get back a URL to visit such as https://seasonal-deck-organisms-sf.trycloudflare.com. Looks like it supports being able to associate it with a custom domain too so you can have repeatable URLs.
Based on the page it looks like you can install Cloudflare's CLI and then run `cloudflared tunnel --url http://localhost:3000`, and you'll get back a URL to visit such as https://seasonal-deck-organisms-sf.trycloudflare.com. Looks like it supports being able to associate it with a custom domain too so you can have repeatable URLs.