My two cents, having done lots of research to upgrading to smart locks, is that apart from the Yale Conexis there is no other option atm in the UK. Alternative are the Yale keypads or from another company, but they should be used as secondary locks. IMO it is better to wait another 6 months to 12 months to see what new smart locks are launched in the UK. There's alot of good options in the US, and inevitably some will make it over or there will be a homegrown copycat.
Yale has a smart lock called Keyfree connected with physical keys, which is now disappeared from their website. It's far too expensive consider the limited functionality it provides and how difficult the software is to use. There are plenty international competitors including major brands likes Samsung, which come with biometric/fingerprint scanner, password, fob and software/remote authentication, at a much reasonable price. It's just they don't fit on UPVC doors, which is a shame.
I agree on the basis of things going down and also there should be some physical way of getting in too. Regarding the Echo support it's there now (with additional stuff) but is working, unsure of Google Home though
Quite like the look of this, but not sure if it would look out of place for my front door: https://www.amazon.co.uk/Yale-Keyless-Connected-Smart-Module/dp/B018KHLA0I?th=1 What are people's opinion on this?