For those of you in the UK, IKEA currently has a steep discount on their GU10 bulbs. I’ve just picked up several dimmable, colour temperature controlled bulbs for £5 each.
They play nicely with HA via a sonoff dongle and ZigBee2MQTT, even down to firmware updates.
They definitely are repeaters. I had issues with a Moe’s ZigBee dimmer. It turned out it was relaying off of an IKEA bulb. When that lamp got turned off at the switch, it killed the link. I ended up using a smart plug as a repeater.
I second this statement. Most of my bulbs are IKEA. I have 4 floors and my ZigBee dongle is on the ground. If they weren’t repeaters, my Aqara motion sensors wouldn’t be working, but they do!