We are very happy to announce that accessibility features have been added to our installation medium with archiso v49. From release 2020.11.01 onward these are available via the 2nd boot loader menu item. A specific installation guide can be found on the wiki.
Many thanks go to Alexander Epaneshnikov who integrated the features from the TalkingArch project into archiso's releng profile, which is used for creating the installation medium.
Note: The boot loader timeouts have been set to 15s to allow blind users to select the menu item as the boot loaders themselves do not offer accessibility features.