Yes, I've use them for ESPHome and other small jobs like lighting controllers, but not for production. They're cheaper than most Arduino or hobbyist breakout boards like Feather. I can't comment on battle-tested, but I've also bought some pretty shoddy ESP breakouts in the past and I've had trouble with unstable WiFi performance when I've meshed them. The PIOs are cool, and better documented than Beaglebone/TI (maybe that's improved). Toolchain is also decent.

I would probably go Atmega otherwise. It's rare I need something in the gap between 8-bit and a dedicated Raspberry Pi. And I'll take some rough edges to support a local company (though for transparency I do hold some stock in RPI).