I think Debian offers a very good compromise. The primary repos follow the Debian Free Software Guidelines (DFSG).

Then they have a separate “non-free” repos for “non-DFSG-compliant packages that are considered important enough to make available anyway”. If you want to be a hardline free software stalwart, you can do that, and Debian supports you. If you are comfortable making a few compromises for the sake of usability, like fonts and device drivers, Debian supports you on that as well.

I agree with PrivacyGuides on why to avoid Libre Kernels

https://www.privacyguides.org/en/os/linux-overview/#choosing-your-distribution

Linux-libre kernel and “Libre” distributions

We recommend against using the Linux-libre kernel, since it removes security mitigations and suppresses kernel warnings about vulnerable microcode.

AND

Proprietary Firmware (Microcode Updates)

Some Linux distributions (such as Linux-libre-based or DIY distros) don’t come with the proprietary microcode updates which patch critical security vulnerabilities. Some notable examples of these vulnerabilities include Spectre, Meltdown, SSB, Foreshadow, MDS, SWAPGS, and other hardware vulnerabilities.

We highly recommend that you install microcode updates, as they contain important security patches for the CPU which can not be fully mitigated in software alone. Fedora and openSUSE both apply microcode updates by default.

That’s why they have miniscule user bases. Ain’t nobody gaming on nouveau, bruh

Didn’t see the original analysis that is used to make that claim, so I can only argue about more general problems, specifically to what scopes one can keep using only software he/she can audity and is free to use. For example, work may require tunelling tools or email/messaging programs which you have no control over. Also the majority of games have at least closed source elements. You also can’t guarantee the sites you access are FOSS or the hardware you have available makes its blueprints or firmwares available and auditable. Also if your setup grows, e.g. using a game controller, USB stick, another screen, etc., drivers needed and/or installed could be a “black box” too as you say.

Such an end is still utopic, too far to reach, so my suggestion would be trimming what can be replaced or ignored while rising awareness (and possible solutions¹) to specific problem, and through that step by step move closer to such a fully FOSS objective.

¹pointing problems without proposing solutions, that I can observe, is a great way to make the listener lose his/her will to tackle a given problem

Source?

The fact that Debian is not on your list makes me doubt that it’s accurate or complete and while I’ve been using Linux as my primary desktop for over 25 years, I’ve never heard of any of those distributions listed.

I don’t really agree with the firmware baked in/firmware loaded at runtime distinction the fsf makes, so I don’t really see the point of not using proprietary firmware wifi cards (like the Intel series), as awesome as ath9k can be

depending on how you manage non-free js these distros are feasible for daily driving though