ソース
https://i.imgur.com/LG8QLJs.jpg

This is what I heard about so-called Xperia 20 (don’t know if it’s the final device name).

Xperia 20 is the “real” first mid-range of new series

Xperia 10 & 10 Plus were developed as X series, supposed to be released at CES (XA3 series), but new management decided to release them as new “number only” series along with X1.

This is why model numbers of 10/10 plus are “I” instead of “J”.

Xperia 20 will have SDM710, LCD, FHD+.
Not sure which countries will have it but not US for sure.
Could be released only in Japan where au is the only operator to carries this model.