Again thanks - this is really useful.
I totally agree with you on screen size / resolution / security etc.
The absence of a headphone jack doesn't bother / affect me but I can see it's a must for some.
I didn't say in my original query but my main reason for considering a move from the Pixel ecosystem is battery life. From the outset my Pixel 2 barely lasted a day and is woeful now. I've learnt to work around it but it's the main reason for wanting to change phones.
The 4a doesn't seem to have addressed this so there's no real reason for me to buy it.
To be honest the more I've thought about it I've decided that I'm just going to get a new battery installed in the Pixel 2 and run it until there's a more compelling reason to change / Google bring our a phone that I can count on not dying at precisely the time you might want a mobile phone to work unless you've remembered to charge during the day / have a piwerbank with you i.e 2am trying to get a taxi home.