Rather than flip floppy slippers (they are a trip hazard, which you really don't want post surgery), a pair of either slippers with firm sides and a proper grippy sole or some pull on (no laces or fastenings) trainers would be more secure for moving around.
I agree with the big nighties so nothing is touching your surgery area and allows for swelling (longer is better as then there's less chance of showing the woman in the cubicle opposite your arse as you slowly turn over don't ask me why I know this - and then some light and soft loungewear/soft bra top for after the first day or so.
Soft, warm socks. BIG knickers.
Hairbrush and hairbands if it's shoulder length or longer.
Definitely ear filters and an eye mask, as trying to sleep when there are lights on and other patients will be difficult.
Lipbalm. Baby wipes (Johnson's are the gentlest in my opinion). A very gentle shower gel, shampoo/conditioner, moisturiser.
Bit of lipgloss, eyeshadow and mascara. Just in case you feel like it.
Then the usual charger, long lead, powerbank, earphones, purse/bank card/keys, couple of pencils/notebook - and all our best wishes!