I haven't tried it yet but it looks good.
I don't understand why a SIM card is needed and what the app is for.
Works well with my oppo phone. I initially had problem but after i uninstalled and reinstalled google find hub app it fixed the problem. I must have had an older version of the app. As for the problem, i was able to add the devices to the find hub app initially but when i closed and reopened the app the tag wasn't listed anymore. The bug was probably fixed in the new version of the app.