Exactly and why there are other distributions:

- GrapheneOS (w/ F-Driod & Aurora)

- CalyxOS

Unfortunately, there are not many providers that will ship hardware with these operating systems, so typically there isn't technical support, aside from community provided.

The two companies I know that are working on that are Purism and Pine64:

- PinePhone with various GNU/Linux distros for mobile: Mobian, postmarketOS and others

- Librem 5 with PureOS