The more I look in to this, the bigger the nightmare.

Finding a new email provider seems likely to be straightforward enough. I do really like the Gmail interface though, so would likely be bringing all the emails back in to Gmail anyway.

But I also use the same google account as my main phone account, so has a tonne of app purchases and (potentially worse) app log ins and progress. As far as I can tell, there isn't a way of transferring those out to anything.

I'm pretty sure you can use a non-Google email to set up a Google account though. If anyone is testing, I'd be super interested to know whether a Gmail legacy account can still be used even if email is transitioned away?

Gmail, Calendar and Play/Android Apps are probably my big uses. Most of the other stuff I think I can either live without or transition easy enough.

But perhaps lesson learnt about vendor and ecosystem lock ins... $120 odd a year to kick the headache can down the road for a year is looking like my most likely option.