When porting a device, you usually take the upstream kernel, and adapt it for minimal requirements of Sailfish OS.
The HADK has a check tool for kernel config options, noting “required”, “optional”, and “forbidden” config options.
It would appear for some adaptations, some or many of the “optional” features are being left out…
I posed a question about this in a Community Meeting a while ago, and the answer was to please file PRs against that repo if you want something included:
See also: More generic kernel configs