Fast boot is just Windows logging you out of your session, then hibernating.
Sleep is keeping the computer in a low-power state with RAM powered on…
Both of these have been known to result in laptops powering on unbeknownst to their owners to perform updates and remain powered on afterward.
I’ve been using a Pinecil which is USB-C powered. It heats up in seconds and the temp can be adjusted easily. The big plus to me is how small it is. It’s so much easier to handle than a standard iron, and the tips are push-in and can be locked with a screw so they’re easy to swap.