Can I use Backblaze B2 as a backup destination and then serve restored files through Cloudflare?

Yes, you can. Backblaze B2 is a viable backup destination. If you need to restore files and serve them publicly, you can upload the restored files to a B2 bucket and then configure Cloudflare to cache and deliver them. However, this isn't a real-time backup-to-delivery solution; it's a restore-then-serve workflow.