They’re waiting for the binary blobs from Sony specifically to make the Xperia 10 IV and 10 V work with any version of Sailfish. This does not apply to the X10 III or earlier Sony phones.
But, as has been said above, the assumption is that Jolla fully occupied dealing with all the C2 issues, so my guess is that it will be sometime yet before we see SFOS 5.0 on any other Sony phones.