I would like to serve any www.domain.com/* route with a specific static HTML page in my server. Is it possible to do this at a CDN level, for example using CloudFlare?
For example:
www.domain.com/12934, www.domain.com/abc/283, www.domain.com all these three render the same static page in www.domain.com/index.html
301redirect rule in the config file of your origin server, however it might be possible to do this using a wildcard and Page Rules. See the CloudFlare docs on this here and here.