To follow up here, the Ikea TRÅDFRI line worked very well once I’d worked out setting up “Mosquitto Broker” and “Zigbee2MQTT” as addons in Home Assistant (and, crucially, removing the “zigbee home assistant” ZHA addon). This worked for bulbs, buttons, and outlets.
Thank’s to everyone for your comments and leading me to something that worked.
I’ve been somewhat out of the loop. What is going on with Lemmy?