It's been a while now but once out of curiousity I tested the text to speech functionality (with my eyes closed) on an iPhone and another device (a laptop maybe?), and found iOS to be more advanced but still lacking. I don't know much about this but it's nice to see improvements. GrapheneOS seems to be a high value project in terms of dollars-to-output.
Even if you don’t value this particular function and even if it’s not as good as Google or Apple, I think it’s important to have viable free alternatives so if Google and Apple rapidly become (significantly more) actively hostile there are viable alternatives.
Does it handle multilingual scenarios? For example 'Your line Сливница - Летище София is arriving'? Don't need perfect pronunciation, need it just to not spell it out letter by letter or hallucinate... (Matcha-TTS' demo on HF is broken and couldn't test for myself)
They accept more than 11 different payment methods[1] for donations and pay most of their devs in Monero.
[1] https://grapheneos.org/donate