One feature I would really love to see in WPMU DEV hosting is something similar to what Instawp offers through their API.
With a single API call, you can deploy a fully preconfigured WordPress website, automatically generate login credentials, and share them with the customer. You can even deploy the site on a subdomain of your own main domain. The entire website is ready within minutes.
I can imagine this being extremely valuable for many resellers and agencies. The concept itself is actually quite simple: deploy a predefined website template to a server through an API call.
I already shared this request years ago because it would allow resellers to connect WPMU DEV hosting directly to their own sales channels and onboarding flows, without relying on the existing reseller functionality from WPMU DEV.
For businesses selling WordPress solutions, prebuilt websites, or sandbox/demo environments, this would open up a lot of possibilities.