Microcontroller like the esp8266 with more gpio
I usually downvote shopping questions, but this one sounds general enough that it could benefit others.

It sounds like you want the ESP8266's bigger brother, the ESP32. It has more I/O, is faster (and comes in dual-core variants) and more/better peripherals than its little brother.

However, if all you need is extra digital I/O, take a look at the many port expanders available. Just go to Digi-Key, Mouser, TME or your favourite sourcing sites and start using their searches. Many port expanders operate over I2C, can support multiple expanders on a single bus, and come with interrupt capability (so the host MCU doesn't have to continuously poll the slow I2C bus for status changes).