It's unfortunate that github.com/RHVoice/RHVoice lacks an implementation of Direct Boot support.
It's beginning to fill the gap of a modern open source Android text-to-speech implementation. Not being able to use it before the initial unlock is a major accessibility issue though.
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There's an open source release of TalkBack with Direct Boot support. It's in relatively good shape but tends to lag about a year behind Google's proprietary accessibility service releases.
TalkBack's Direct Boot support is no good without a TTS service for it to use there...
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GrapheneOS will have TalkBack + Switch Access included again in the next release. These used to be included but this is part of what got lost when reviving the project after being screwed over. RHVoice would need more review/changes, especially since it'd be enabled by default.
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