Hi Panchita....with skinny shapes that are not easy to appliqué you can do a straight stitch maybe a little smaller than usual along all the edges...... yes ... if it is washed lots it might get some stray threads, but you can trim them off..... it isn't worth too much frustration trying to use a fancy stitch on such small pieces.
And yes.... it is hard to be patient for the new block, especially with so much "at home" time.