Having purchased bunches for film and TV you're looking for "Twin Long". Usually you have to go with solid colors (beige, blue, green). otherwise we had to "short sheet the beds or double up.
Fitted will be tough, hospitals are all about "cost" so they buy a bunch of flat sheets and double the bottoms and call it a day.
You can buy from a medical supplier (Medline) but you have to buy by the dozen. Sometime 6dz at time.
I used to buy from these guys but you have your choice between beige (bone) or blue. And they sell by the dozen, ask for twin long, they have them or can suggest someone who can get what you need.
https://acmelinen.com