I think you would get more suitable recommendations if you told us what your use cases are. Did someone else give you those requirements? Are you new to Linux?

Arch, Slackware current (KDE), Suse tumbleweed, Debian sid and Fedora tick all the boxes but I wouldn’t recommend Arch nor Slackware to someone who never used Linux before, nor I would recommend Debian sid for desktop usage (unless you know what you’re doing) because its packages are not controlled by their security team.

Free and open-source. Receives regular software and kernel updates.

All of them (desktop). The difference in updates is between a rolling release or non-rolling one.
Rolling means they receive updates to software and kernels continuously as soon as they are released, you always have the latest versions but that could lead to instabilities, non-rolling (or stable) are updated less frequently so are more stable, which one to choose depends on what you need to do with it.

Avoids X11.

Fedora, Suse, Ubuntu, Slackware current, Debian, Arch, if you choose GNOME or KDE you’ll have Wayland as default AFAIK, probably others.

Supports full-disk encryption during installation. Doesn’t freeze regular releases for more than 1 year.

All of the above.

We recommend against “Long Term Support” or “stable” distro releases for desktop usage.

LTS is a version, not a distro. Distros that offer LTS versions also have a non-LTS ones, get those and you’re fine. Tho not wanting a stable is weird, they can be the best for desktop usage depending on what you need to do.

Supports a wide variety of hardware.

That depends on the kernel, all kernels support a wide variety of hardware, non-LTS versions are best for more modern hardware.

Preference towards larger projects.

All distros mentioned are large projects, Debian is probably the biggest, it also supports several different architectures.