Majority (80%+) of my Zigbee devices act as routers, light bulbs, sockets, switches, etc. Only sensors and controllers are end device nodes.

> One of the biggest issues with Zigbee is vendors selling devices that only work with their gateway.

Sold as such, but work as generic devices just fine, no issues. You just need a Zigbee dongle and ZHA, Zigbee2MQTT or deCONZ.