@Privacy2 Good and reasonable questions.
We do remember that. This is about the control. The firmware you listed does not affect the running PureOS. It by design cannot interfere with my RAM or browsing. I can treat it as a part of (already untrusted) cellular / WiFi network. I have an opportunity to replace it later without replacing the whole device (possibly by replacing the M.2 card, when it’s available, or reflashing).
Android does indeed have a lot of free software. But the nonfree software which it runs, removes the control from the user: you can no longer upgrade your Linux kernel, you can no longer be sure that your operations on the device are safe. It has access to everything you do; your only choice is to trust it or throw away your phone.
Yes, but which other companies advance the mobile GNU/Linux as much as Purism? Everyone could do it, but no one is doing it.
Which tablets can run exclusively free software and latest Linux kernel?
This is a software operation. If you do not trust your software (and I do not trust proprietary software from Google or Samsung!), you cannot be sure that “airplane mode will fully disable the cellular radio transmit and receive capabilities”.
On the other hand, I am sure that the hardware kill switch switches off the modem on Librem 5, even if it’s infected with malware.
This is a completely different threat model. I understand people who choose to follow it, but you should not expect that everyone does. I do not trust Google’s firmware, full stop. I prefer to have “less security” but be able to run fully free software. Why can’t I run GrapheneOS on Librem 5? To me it looks suspicious: GrapheneOS effectively promotes Google control over users.