Just to make sure I hadn’t done something stupid I removed the integration completely and started over. Followed the instructions again with the same result - no device gets created.
I downloaded and searched my logs and the only mention of the integration was:
2023-08-03 21:11:54.392 WARNING (SyncWorker_2) [homeassistant.loader] We found a custom integration samsung_soundbar which has not been tested by Home Assistant. This component might cause stability problems, be sure to disable it if you experience issues with Home Assistant
However, I noticed the links in the instructions were to the old token and Smartthings backend which have now been deprecated but it appears the API calls are still the same so probably irrelevant