Openness isn't binary. One significant step is support for the mainline Linux kernel. Another significant step is free information about the hardware on a high-level, such as PCB schematics and documentation about the used chips. Here are some projects that I'm aware of:

Mainline Linux:

https://pocket.popcorncomputer.com/

https://necunos.com/shop/

Mainline Linux + high-level hardware documentation:

https://puri.sm/products/librem-5/

https://www.pine64.org/pinephone/