🚀 go-pugleaf

Output impedance of your linear regulator at a few microhms seems difficult
to achieve.  When I've done power supplies (low power), 100 MILLIohms
was an acceptable interconnect R.  So, if the output leads on your
power supply are the same as (say) the set of test leads on a voltmeter,
you can add a tenth of an ohm to your output impedance right there.
Tough to say what you can do to get down to microhms.  Maybe use gold and
special connectors.  A standard PC type connector could give you 5 milliohms
by itself - three magnitudes too large.

General tips are to keep your output leads short - lead inductance will
increase output impedance, even at 100 kHz.  Also use bypass capacitors,
of course -- tantalum and ceramic in parallel should be good enough for
100 kHz -- and put them close to your load.