Its the only way to be sure.
I'm not abandoning my "what memo?" game any time soon, although with a second player now involved and not always having him available, I had an idea last night:
How viable is nuking the entire galaxy? That is: setting off a Mk3 nuke.
What survives, what generates income, what can you still build.
As far as I've determined so far:
You can build mk4 units (advanced factories/starship constructors do not require supply)--however the Mobile Space Dock will allow the construction of Mk1-3 fleetships. You can build experimental and core units (fabs don't require supply). Spire campaign units and spire asteroid units are immune to nukes. You can construct orbital command stations in order to capture capturables (that were not destroyed) although you cannot generate supply nor generate power (both the Energy Collector, Matter Converter, and Z-Power Generator require supply and Cryopods are not immune to nukes). Home Human Settlements do not require supply and are immune to nukes, however, generating 50 metal income per second each (a trickle).
Spire cities generate piles of income and are immune to nukes...but require supply. Damn.
Rebel Colonies, Spire Civilian Leaders, and Gravity Drills are not immune to nukes.
Z-Reserves, Distribution Nodes, and SuperTerminals are immune to nukes.
All turrets require supply.
Unknown if scrap income can be collected on a nuked planet yet. Possibly?
The only way I can see this even being possible is with the "No Waves" toggle enabled. There's some opportunity for AIP reduction (although at a base 5000, its probably irrelevant) and a handful of one-time infusions of resources (distribution nodes, Z-Reserves).
My thoughts on this kind of attempt pretty much involves getting two to three spire cities, building all of their units, building as many starships as possible (including mk4), building as many mk5 units as possible, capturing a regen golem, then nuking the galaxy. From there repairs will be minimal and slow, with very little in the way of re-fleeting (only Mk4+ units could be constructed, even if 99% of the economy is scrap based). Assuming one could even power anything. With the home command station and an EconIII foldout, we're looking at an energy cap of 36,000.