Thanks all for your help and advice.
I now have the Tama port of SfOS installed, updated to 6.0.0.67, and running on my XZ2C. I’ll try using it over the next couple of weeks, though not yet as a daily driver, at least until I can find suitable replacements for the Android apps I use every day. It’s also an opportunity to look at what apps I use and see if I can ditch a few. That may become another thread if I can’t find an existing one.
I will also keep an eye open for Xperia 10 iii devices on Ebay and Backmarket, so I can see how Android apps run ‘natively’ rather than via Waydroid.