Long back i heard about HMD providing unlocked bootloaders for few of their devices. Why is Jolla not keen on adapting Sailfish for Nokia hardware and concentrating only on Sony? I don’t contempt Sony though, it is still a good option. But what is the reason for not trying out an alternative option? Moreover, Nokia devices can entice more people then Sony devices could.
This has been discussed many times. Apart from HMD promising, afaik they did not provide anything. Also SFOS needs quite more than an open bootloader. There are legal issues, too. See the thread for xperia 10 II f.ex.: XPeria 10 II + SFOS
And now, the SFOS is available in xperia 10 II officially
Maybe this topic about possible new phones is a good read for you (it’s pretty long, but the automatic summary of Discourse is good enough to get tge most relevant parts of the discussion )