I contacted HMD. Here is what I got:
"Greetings from HMD Global Support.
We value the importance of your concern.
In response to your concern regarding HMD skyline, we would like to inform you that kernel sources and ROM are available on web and you can get them by internet search, we regret to inform you that we are unable to provide them directly from our end.
Please feel free to connect us if you have any further questions or queries.
Our endeavor is to ensure continuous improvement in Consumer experience.
Thank you for contacting HMD Global Support
Always looking to serve you better.
Thanks & Regards
HMD Support"
Bootloader is unlockable.