It is definitely not available during the installer, I just did one last week. Ended up using an answer file which put me directly on the desktop after installation so I can’t comment on the out of box experience.

I think opposite. OOBE should be fine, installer is not because USB devices and sound devices are not getting enumerated properly. For some this has also meant no input which is how the mainstream world got a hold of this. For us sadly it means no Narrator unless someone grabbed a retail non-updated Win11 image, IE, not made with media creation tool which has updates slipstreamed into the installer.

Not sure where you heard this, but I reinstalled Windows only a couple of days ago, using an ISO I created with UUP Dump based on the latest 25H2 release. Narrator worked fine. You can't speed up the voice and some of the speech codes leak through to the TTS, but it still works on the installer and advanced startup. The OOBE is a normal login session, so Narrator will work but you can also just shift-F10 and start a portable NVDA. I always use English US instead of English International because the international edition embeds a different Narrator voice, and IMO it's less intelligible. The broken rate adjustment and leaky speech tags are annoying, especially if you're trying to get anything done in cmd, but it's workable. I'd love to figure out why NVDA won't run in that installer/recovery environment. Something about its side-by-side configuration being invalid. But blind Windows installs are, as far as I can tell, working just fine.

@simon For context, I was trying this in a arm VMware fusion virtual machine which doesn’t have the easy install feature, so that might be a factor. speech did work after the installation was completed