I would love some PSU metering ability, to see actual data about how much juice my PC is pulling down. Other than getting a kill a watt meter, how could one go about this?

They make "digital PSUs" like the Corsair AXi series that can talk to your PC over a comm port.

Some UPSes can show how much power is being drawn by everything connected to it, in this case presumably your computer.

You probably want a UPS anyway if you've got a power guzzling (and thus presumably expensive) machine.

Many server PSUs and motherboards have a SMBus or similar interface for monitoring. Quite rare on consumer parts, sadly.

Knockoff meters are like $10 on Amazon. Not a bad investment.

I have what is probably a close spiritual cousin of one of those, and while it even touts a power factor display, it also loves to show ridiculously high values during idle consumption for anything involving some sort of power electronics (not just for my computer, but for example for my washing machine, too – it shows sensible values while the heating element runs, or when the motor actually turns, but in-between it shows nonsensically high values).

It is a few years old, though, so maybe by now quality standards have improved even for those kinds of cheapo-meters…

Calculate it. You'll have kW/hr costs for electricity which depend on where you are and can ballpark power based on fraction of the time it's running and the components in it.

My standard dev machine is ~1kW flat out, ~500W most of the time, probably 100W idle. Runs for about eight hours a day. Say 500W is the average, suggests 4kW/hr a day. That's about $2 a day in the UK.

(those power numbers are relatively high - it's an elderly threadripper with two GPUs)

I think that 500W average is the tricky bit. When web browsing for example, my laptop (linux+intel) seems to spend 99% of the time in the C1 halt state, according to i7z.

I can say that when my son left for college last fall, our electric bill dropped about $30 a month compared to the months he was here (after adjusting for seasonal heating/cooling costs). He has an i9-12xxx gaming rig with two monitors. A Prusa 3D printer that gets a lot of use and a few other gadgets and such.