Electric pumps & air con

Electric ancillaries are more about emissions & not needing to use as many hydrocarbons to run them when they’re not needed … ie. can be turned off ‘cos they’re electric. For max power, I doubt there’s much gain to be had … you might measure a kilowatt on a dyno, maybe, but you won’t feel it when driving.

People also go electric power steering to make room for a supercharger.

As above, probably not worth the effort for what power you'll gain. A good service may net more benefit.

It would be difficult to justify the work, complexity, and expense of changing those things to electric unless there's significant gains to be had from weight loss, system efficiency, or space. How much current are the electric replacements going to draw? And, how much more efficient is the electric replacement device over the mechanically driven one, if at all?
AFAIC, that's what it comes down to.

Other improvements in technology aside, usually you can just count the number of times you have some kind of energy state change, the higher the number the harder it is to win the efficiency race.

Electric power steering has a distinct advantage over hydraulic in that it can be packaged much more compactly, and for modern cars also plays nicely with assistive technologies that want to make direct inputs to the steering, whereas to retain a hydraulic rack you would need to still add electric servos to have those features. So why have both when you can just drive it all with one electric unit, and have the electric unit be simpler and smaller and cheaper to manufacture and more flexible in its packaging. Electric also allows for all sorts of other modern fanciness, like you can dynamically control steering feedback.

A/C is a heat exchanger system, so however you approach it, you have to compress gas. If you drive a compressor with the engine directly, you are burning fuel, producing kinetic energy, and then using that to energise the refrigerant. If you had an electrically-driven compressor, you burn fuel, produce kinetic energy, convert that into electrical energy via the alternator, then convert it back into kinetic energy using the compressor motor, then use that to energise the refrigerant. It's the same but with more steps, which usually means more entropy.

The case for electric AC in an ICE vehicle is that you can operate the compressor fairly independently of the engine. This means you can amortise the load of the compressor, and maybe exploit different driving modes (e.g. you could load down the alternator on decel, similar to regenerative braking, and unload temporarily when you want max engine performance).

But, modern compressors have already thought of this, and modern cars these days tend to all use variable displacement compressors. This means the ECU can exercise fine-grain control over the compressor load based on cabin demand and engine demand.