I have to answer to this post directly.. First of all: I am a member of the European free software foundation. I am since over 10 years.

Using those distributions is, sadly, a security risk!

Everybody must be absolutely clear about the fact that CPU microcode updates are property blobs, and therefore removed by those projects.

This means: Your CPU runs with only the build in firmware and is most likely vulnerable against many CPU level attacks. CPU bugs can only be fixed with microcode , and if you drop those from the systems you leave the systems vulnerable.

Full free software distributions are a important, but very esoteric.

OP claims even the kernel itself is non free software. So let me just cite the kernel archive

Is Linux Kernel Free Software?

Linux kernel is released under the terms of GNU GPL version 2 and is therefore Free Software as defined by the Free Software Foundation.

I heard that Linux ships with non-free "blobs"

Before many devices are able to communicate with the OS, they must first be initialized with the "firmware" provided by the device manufacturer. This firmware is not part of Linux and isn't "executed" by the kernel -- it is merely uploaded to the device during the driver initialization stage.

While some firmware images are built from free software, a large subset of it is only available for redistribution in binary-only form. To avoid any licensing confusion, firmware blobs were moved from the main Linux tree into a separate repository called linux-firmware.

It is possible to use Linux without any non-free firmware binaries, but usually at the cost of rendering a lot of hardware inoperable. Furthermore, many devices that do not require a firmware blob during driver initialization simply already come with non-free firmware preinstalled on them. If your goal is to run a 100% free-as-in-freedom setup, you will often need to go a lot further than just avoiding loadable binary-only firmware blobs.

https://www.kernel.org/faq.html