@holy that halium-gsi image is super old and should not be used anymore.
You should take a look at the android 10 repos under https://gitlab.com/ubports/porting/community-ports
.
You could clone a repo, which matches your device best. The adjust it to match your device configuration.
You need to apply kernel patches to your kernel, to make UT boot. You could also sneak into other kernel repos for that.
And also follow:
https://docs.ubports.com/en/latest/porting/build_and_boot/H9_gitlab_build.html