$10 a day is likely far too high for a hobbyist or open source developer.
However for a professional developer $10 a day for something that's much more helpful than Copilot could be just a rounding error. Especially if that "much more helpful" translates to a significant productivity boost over and above Copilot.
Big companies aren't likely to go for something like this because of IP and confidentiality concerns. But for a solo or indie developer I could possibly see it.
Does it perform a lot worse with GPT 3.5? That could drop cost hugely if it's close to as good.
Also it remains to be seen how GitHub Copilot X will perform, whenever they release it.
End of the day, it's a reall cool experiment. Thanks for sharing!