I do a lot of appliqué. Fused, raw edge, machine appliqué. Generally my go-to fusible ( I purchase it by the bolt) is Heat n Bond Lite. I either use a small zigzag or blanket stitch around each piece. I’ve been doing this for years. I’ve never really had any problems with fraying edges.
If you choose to do needle turn hand appliqué remember to add a seam allowance to each piece.