[lexlash]

The Home Assistant-branded ZBT-1 [0] is $30ish and, if your goal is Home Assistant, you're probably better off going that route especially now that IKEA is going all in on Thread/Matter (which the ZBT-1 supports in addition to Zigbee.)

I do have that particular Sonoff dongle - as well as a ZBT-1 - and I can vouch that the dongle works as well as the Hue hub it replaced, controlling a couple dozen lights.

(Obligatory prime-day-is-not-much-of-an-actual-discount so don't worry if you miss out on this sale - https://camelcamelcamel.com/product/B09KXTCMSC)

[0] https://www.home-assistant.io/connectzbt1/

[mook]

The docs for ZBT-1 seems to indicate that it can only do one of ZigBee or Thread at a time (that is, you must choose one of the two firmwares to flash), right?

It looks like there's third-party work to make Sonoff ZBDongle-E (which is _not_ the linked device) do both at once, but that's not officially supported…