This firmware for DIY end devices or routers is exceptional, I highly recommend. I’ve only used it with CC253x devices, but I understand he supports the CC2652 family as well. There are not as many development board options for the CC2652 device as for the CC253x devices. I’ve had good success with CC253x both on battery and mains powered, and they are very low cost and available today. Do get a couple and CC debugger all for well under USD 50 and experiment with what kind of I/O and sensors you can bring into your zigbee Home Automation environment.
I’ve only used this firmware with devices attached to my zigbee2mqtt setup. This firmware is very well supported by the zigbee2mqtt folks. I have yet to see if the integration is as good with the firmware attached to a ZHA or Hue zigbee setup.
IMHO, for end devices and routers, I did not think the CC253x is going to be obsolete for a very long time, they just work and are solid. The basic CPU in them is going on 30 years already and shows no sign of not being used in many IOT and IIOT applications. For coordinators, I agree the CC253x is at end of life, just too underpowered.
Zigbee Configurable Firmware v2.5