No, it is not dumb. My second link was just an example to a fix of one particular laptop where this issue occurred. I mentioned all this just to point to the issue that might be causing your problem. I’m afraid this probably does not fix it for you. Maybe it has been fixed with a more recent kernel. You could check which version you are running (by running uname -a from a terminal) and maybe update to a newer one if your distro allows that. Alternatively you could downgrade the kernel to a version before this issue was introduced (a 6.10 kernel should work okay). Of course downgrading should only be a stop-gap solution.

Yes. Apparently the issue happens with both internal mics and mic connectors where you attach your own mic. The seconds link I provided points to a fix for a specific laptop that fixes a non-working internal mic.

It is probably due to this change in the Linux kernel. That broke analogue microphone inputs on lots of systems. After that change, there were quite a few additional patches fixing those problems on individual systems (e.g. this one), but there are still lots of broken setups around. I have no idea what the original change was about exactly. It appears to have broken more things than it has fixed, but what do I know.

Can anyone explain to me if a headless chrome browser is dangerous the way a regular chrome browser is?

Almost. You want to make sure to keep it as up-to-date as you would a regular Chrome browser. It does almost everything a regular Chrome does, including running arbitrary scripts on websites.

The guide mentions:

Your ISP will give you the first 64 bits, and your host machine will have the last 64 bits.

This isn’t correct. While some ISPs do give you the first 64 bit (a /64 prefix), this isn’t recommended and not terribly common either. An ISP should give its users prefixes with less than 64 bit. Typically a residential user will get a /56 and commercial users usually get a /48. With such a prefix the user can then generate multiple /64 networks which can be used on the local network as desired.