I used to have an FT-221 tricked out with a hot front end. Solar
noise would run the S meter up to well over the S9 mark and you could
even see the galactic plane passing through the antenna pattern.
Needless to say, it heard well on terrestrial 2m SSB.

That is no mean feat!

You better believe no mean feat! I worked off the moon on 432 MHz back in
the late 70's. Sixteen 16 element Yagis (calculated gain ~26 dB) and an STA
from the FCC to use 5 KW as long as the antennas were pointed above 25
degrees elevation. (Protecting Eglin radars some 200 plus miles away.)

I could consistently manage some 4, 4-1/2 dB of sun noise off a quiet sun
and not one smidge more even with a mast mounted GaAs Fet preamp supposedly
with some 0.8 dB NF.

I DID however, at around the same time, own a 2 meter Jap all-mode
transceiver that I happened to measure the "S" meter accuracy with an HP
signal generator. It turned out that 2 uVolts was "S"-1. THREE uVolts was
"S"-9.

W4ZCB