Zigbee2mqtt has a huge number of supported devices (here's their official list [0]), which can also be expanded if the existing mappings don't work.
It took me a minute to find, but the full MQTT structure is detailed here [1], and then individual devices detail what they expose on their page (e.g. this [2] is a random Sonoff temperature sensor). This means that the topic "zigbee2mqtt/sonoff-temp-example" will just have a simple JSON message with '{"humidity":46.93,"temperature":21.73, ...}'.