@clairev I got the aviva, aviva nano and a Bayer USB. I too thought the nano would be great but I have had technical issues with them including returns. It may be isolated but I no longer trust the meter.
I switch between the aviva and the bayer at the mo. I find the bayer more sensitive than the aviva for some strange reason, but guess it is each to their own. Unfortunately I can not get either the wavesense nor the freestyle.. Boooooooo! “buggger” Booooooooo!