Running a Bitcoin node has always been possible and rarely been pleasant. Umbrel's answer was to stop treating it as a systems administration exercise and make it an operating system with an app store, so that installing a node, an Electrum server, a Lightning node or a media library is a click each.
umbrelOS describes itself as "a beautiful home server OS for self-hosting", built so people can "enjoy the convenience and benefits of the cloud, without giving up ownership and control of their data". Bitcoin is one app among many now, which is worth saying plainly: this is a self-hosting company that started in Bitcoin rather than a Bitcoin company.
The founders are Mayank Chhabra and Luke Childs. Chhabra announced a $3 million seed round on the project's own community forum on 29 October 2021, writing that the money would go on building a team, and pointing to a longer post about "how @lukechilds and I met, why we started Umbrel". The company's terms of service name the entity as Umbrel, Inc. and set governing law as Delaware. No public registration record was found beyond that, so this entry records the corporate form and leaves the founding year off rather than guess it.
The licence is the thing to read before assuming this is ordinary open source. umbrelOS is released under the PolyForm Noncommercial 1.0.0 licence: use, fork, modify and redistribute are permitted for personal and nonprofit use, and commercial use requires a separate arrangement with the company. That is source-available rather than free software, and it is a deliberate business decision, not an oversight.
Hardware is the other half of the business. Umbrel sells Umbrel Home and Umbrel Pro, and the same software installs free on a Raspberry Pi 5 or an x86 system, so the hardware is convenience rather than a lock. If Umbrel the company stopped tomorrow, an existing install would keep running and the code would still be there.