These things aren’t bad, I’ve got a few that I use sort of successfully, but the speaker and mic aren’t very powerful. I was thinking of building one with an ESP32 and i2S (not i2c, that threw me off too) speaker/mic, but I’m wondering if I’d be reinventing the wheel here if there’s a better alternative already out there.
Check out Onju. You can buy the PCB from pcbway or there are some other options coming: https://www.crowdsupply.com/onju/onju-voice