Operating systems
Libreboot officially supports booting into Linux-based operating systems and BSDs.
Can I use Windows?
In theory, yes, you can use Windows 10 and 11. You will need to bypass the TPM 1.2 and SecureBoot requirement to use Windows 11.
Windows is proprietary software, which means that you do not have the freedom to use, study, adapt and share the software in any reasonable way. This is contradictory to the goals of Libreboot, are not officially supported, and the community cannot provide support for them.