FSF did not create Libreboot

Indeed (as I said) they did not create it, they made a shittier version of it, called GNU boot. Or I guess maybe not "the FSF" but devs under their umbrella. I think Linux Libre would be a better example. Or all the crappy "FSF approved" distros listed on their website.

it’s hard to create a chain of trust without trusting the hardware

That's true but that's not really their stance. They trust the hardware and the software running on said device, as long as they don't have access to the software. Microcode updates are an example of this. They don't like microcode "blobs" in the kernel but trust the outdated vulnerable microcode running on their CPU.

I would rather use a deblobbed device than wait for obscure security features that provide no real-world benefit to my use case.

I would not. I would prefer not to get hacked by spectre type attack. I also don't like broken virtualization on my CPU and don't want my CPU to destroy itself by high voltage.

But yes, I agree that to trust the software, we need to trust the hardware first. This also means that there is basically no "Respects Your Freedom" hardware. Every such hardware runs proprietary software which the user cannot see. And even if it ran no such software, it's still just proprietary hardware, which we cannot study, create derivatives, etc. If I ran the FSF, I would acknowledge that there is nothing but grey area, instead of drawing an arbitrary line through the grey area.

Going back to phones, I am just worried that the Librephone project will focus too much on moving the proprietary parts from software to the hardware instead of actually helping users to get more freedom.