Supported Bridge Pose
Supported bridge is a great gentle backbend that passively releases the muscles along the front body, many of which support your spine. Place a block (or pillows or books) under your hips (not your low back) on either the low or medium height. Legs can be bent with feet flat or out long as pictured.
Gate Pose
Side stretches release the oblique muscles and all sorts of muscles that move and support the spine. Sometimes these muscles can be chronically tight on one side of your body, throwing you out of alignment. When doing gate pose, be sure to do both sides even if only one side feels tight.
Supine Twist
Supine twist is a gentle twist that stretches many muscles that move and support the spine, including ones that are very close to the spine itself. This pose can feel even better with a block or pillow between/under the legs.
Star Pose
This is a gentle forward fold that allows the muscles that hold you up all day to finally let go and relax. Unlike in bound angle pose, the feet should be a few feet in front of the hips and the spine should round gently down. You can rest your head on blocks/pillows stacking them if necessary to create more ease. If accessible, you can also rest your head on your feet.
Seated Spinal Rounding
This forward fold is a little deeper (those with herniated discs be aware) but can be really satisfying for lengthening some of the muscles of the back. Clasp the back of your thighs or hug your arms around your thighs and sink your weight backwards while you round your back.