This is a feature in WPMU Domain Mapping which includes integration with eNom but I don’t think this was mentioned other than the DM plugin before… and we’re a Platinum Reseller, so get decent rates. We can offer a free domain name with higher plans (one for the main site) and to buy for any site. This is done from inside their WP Admin area in the domain mapping so no need for anything public in design but this is a feature.
Every best practice starting with Cloudflare Pro for their domain and DNS before traffic even comes to our server. Then our servers are high-availability clusters, completely optimized Nginx, memcache, redis, gzip, wp-rocket, CDN served files, etc. which can often serve without even calling PHP for static content.
Our cloud servers can instantly add resources as needed which is why we don’t restrict customers to 512MB or 1GB of RAM like the competitors. Each site can handle thousands of hits per second which is why in our strategy we would rather focus on monthly hits.