Unfortunately, the Sony Open devices seem to be hard to get (at least in Oz). I use LineageOS but there it's only available for a limited set of devices :(
Xiaomi are pretty good, many of their mid range models are pretty cheap and they do have manufacturer supported unlocking (I have 2, Poco X3 pro and the Poco f3, because the f4 is trash)
Both are well supported by lineage and co (I don't use lineage because they refuse to include signature spoofing so microg doesn't work properly) but otherwise fine.
