Problems recording the line output on laptop

[MR ZenWiz]

I have a 17" LG Gram laptop on which I run Xubuntu 20.04 with Audacity
2.3.3 installed.

I also run Xubuntu (20.04 with Audacity 2.3.3) on my (custom made, i7
based) desktop.  I have little or no trouble with the recordings on
the desktop.

On the laptop, the only mechanism I have found that works to record
something in Audacity insists on using the laptop's built-in
microphone, which is fine under most circumstances.

However, I would like to record the line input coming from, say, an
audio I'm playing in my browser or something else I may want to record
but not have to play it on the speakers so the built in mike can
"hear" it.  I don't see how to do this.

On my desktop, this is fairly simple - I just use the "default" mike
that's setup on installation.  I'm not absolutely sure, but I also
think there are no other special flags set to allow this.

On the LG, this is not the case - no matter what I do, I can't get
Audacity to record from the line input - ever.  There isn't any line
input jack, adn the "speaker" jack is a headset jack (speakers & mike,
and I think LG says the mike isn't set up - it only uses the built in
mike).  For speakers I have LogiTech USB-only speakers that don't have
or need the usual headset jack plug.

Is there something about laptops that makes this harder that I
(clearly) don't understand?  I had similar problems with an older HP
laptop, also running Xubuntu (16.04 and 18.04), but I found a way
around them.  The LG refuses to allow this no matter what.

For the record, LG does not acknowledge that I can even run anything
other than the original installed Windows 10.  As a long time Linux
user (and engineer), I found a simple enough way to make that work as
a dual boot.

Is this an Audacity bug I could report (and, if so, what other info
should I provide)?

If not, can anyone tell me what I'm doing wrong here?

Advice?  Comments?  References?

Most appreciated.

Mark