> That’s a tenner a month for something that’s only really useful in emergencies.
Depends what you mean by 'emergency'. You can call the emergency services without having an eSIM set up, just as you call 999 (or whatever the emergency number is where you are) from any phone with or without a SIM inserted (or unlocking the phone beforehand). It's mandated by the regulators. Indeed, calling the emergency services is the only time a soft SIM iPad will allow you to make a voice call over a cellular network.
So, this watch having a cellular chip could be useful should you be out jogging and break an ankle, or feel sudden shooting pains in your chest - both events that would warrant an ambulance.
But yeah, lesser 'emergencies' such as ringing a curry house to order a takeaway aren't covered - you'll need the EE tariff as you say.