I just recently got a foam roller under guidance of a PT and I'm finding it super helpful for stretching all the way down from my hips up to my upper vertebrae just above my shoulder blades. It's very helpful for the kind of hip/glute/low back pain I've been experiencing. You'd want to get a high density foam roller WITHOUT any nodules or massage points- just a big ole foam cylinder. Additionally, if you get one long enough, you can just lay on it long ways so that it runs down your spine and supports your entire body weight from head to hips, then use your legs to stabilize yourself. You can then put your arms out to your sides to help get a stretch in your chest while also giving your back a chance to release tension from our normal hunched/forward oriented posture. Depending upon where you place your arms you can stretch slightly different areas too, but it's easier to feel that than explain it via text. I'm not strong enough for every foam roller exercise just yet, but maybe you'll find YouTube tutorials easier to follow along with if you've got some better baseline strength.

As for exercises, I've been doing bridges where while laying on my back with my knees bent, I just lift my hips into the air and hold for a few seconds, then slowly release and let my hips back down. If this is too easy for you, raise one leg and keep it extended and do the lifts one leg at a time. That and planks have been helping my lower spine a good bit.