Can a bias strip be hand knitted for applique on a pillow sham? As if following a narrow Celtic knot design?
Knit a long narrow strip/design as desired. You could do the whole thing straight and bend it to attach to your pillow OR you might consider doing short rows/corners turns to help go around the pillow's edges.
Depending on how 3-dimensional you wanted the design to be, you could use I-cord to weave the knot pattern. It can be knit with very fine yarn over say, 3 sts so that it's rather flexible.