This is the best summary I could come up with:

As part of the effort for enabling UEFI support with ReactOS, an open-source operating system re-implementing binary compatibility with Microsoft Windows, a development build of ReactOS is up and running on Valve's Steam Deck handheld game console.

While not suitable for any serious gaming yet with the binary compatibility of ReactOS for modern Windows games still being rather limited especially among Windows device driver support, in early experimental form this open-source OS is up and running on the Steam Deck!

For months there has been work on UEFI support for ReactOS that can be tracked via this pull request.

The ReactOS crew shared that with the work-in-progress code one of the developers is able to run ReactOS on the AMD-powered Steam Deck: Behind the scenes, @The_DarkFire__ has been working on bringing UEFI support to #ReactOS!And here's a surprise by him: With a PR, ReactOS running in Steam Deck!!

!Work in progress.For more information, see here: https://t.co/woLpr8PY6U pic.twitter.com/1DKQKJUXG2— ReactOS (@reactos) September 13, 2023 While it may not be entirely practical at this stage given the limited device driver and modern game binary compatibility with ReactOS, it's an interesting milestone nevertheless for this open-source project.

The original article contains 192 words, the summary contains 193 words. Saved -1%. I'm a bot and I'm open source!

ReactOS has always been kinda interesting to watch. I am all for another FOSS OS, while I get this is kinda unique use case it's still interesting to watch.