You can easily get ESP8266/ESP32 boards with header pins already soldered on; combine this with some DuPont cables (as I’ve just learned they’re called) and you can start messing around with things without much soldering at all. You can also connect to e.g. LED strips and simple sensors in the same way.

See this kit for example: https://a.aliexpress.com/_EyZhdw5

They're pretty great and compatible with most things. ESPHome [1] is a great resource for getting ESP32's working nicely with HA and you can find lots of projects using it to learn from.

You'll likely need to do soldering if you want to connect sensors, batteries and the like.

Personally I really like what SEEED Studio [2] does with their ESP32 boards and they have nice docs.

1. https://esphome.io/ 2. https://www.seeedstudio.com/home-assistant

You could get a dev board and a breakout board on aliexpress for less than $6 - this way you can get away without any soldering for most use cases. And if you use esphome and homeassistant, pretty much all code is just configuration and setup in homeassistant.

https://www.athom.tech/ are selling a lot of pre-flashed gear in nice casings which is essentially "plug and play ready to go" - out of the box you can wirelessly flash them.

So depending on what you're doing, they're an excellent place to start.

M5Stack/M5Stick products and Grove accessories comes with batteries onboard and connects with cables

M5stack makes nice plug and play hardware too, almost like Lego https://m5stack.com/

The sonoff line is typically pretty hackable and now has etl certification on some of their products. If recommend something like this if you want to switch mains voltage. I use tasmota, which is similar to esphome. The tasmota wiki has disassembly and flashing info. I've always used wires to flash mine but I think there's a software only flash method. The s31 can be flashed with some spring hook probes and the appropriate rs232 cable (3.3v on the data lines iirc). Some of the in wall line need a few pins soldered on (typically 4).

Tasmota has a setup package of you don't mind manually setting up each device. You can also configure them with code if you learn a little c and platformio. At this point, I batch my devices and flash them with wires for initial configuration (Wi-Fi, mqtt, etc), then run updates wirelessly using an http server on my network and mqtt to coordinate.

Side note, the esp8266 is older and less powerful than the esp32. In practice, the esp8266 can't handle https but the esp32 can. This has never been an issue for me and most of my devices are 8266.