I always buy separates as I don’t use top sheets, so just look for these rather than brands that only sell sets. Then buy an extra pair or two of pillow cases and swap his out daily; use a pillow protector too so it’s not all going through into the pillow.

The other option is to buy a bunch of soft hand towels to lay over the pillow and swap those out daily, it can be more comfortable as it’s more absorbent than a pillow case.