DNOS reads as a network operating system, or as a distributed OS, or as DNS-adjacent infrastructure. Any of those puts it firmly in the technical world, which is where a short four-character name like this belongs.
There’s also a specific energy reading: distribution network operators are the regulated companies that run local electricity grids, and DNO is standard sector shorthand in the UK and several other markets. An organisation, platform, or association serving them would find the name already in use among its audience.
On the .org, the association and standards readings are strongest. Technical bodies, open-source projects, and industry groups all use that extension, and a compact name suits a body whose full title nobody says out loud.
Four characters, no hyphen, no digits, and it looks like a system component, which for a technical buyer is exactly the right impression.
The name is listed for sale. Offers considered.