Fiber supplements without carbohydrates??

This is a very helpful forum, I’m 54 always trended toward high cholesterol and now that I’m over 50 I’ve got total cholesterol 262, LDL 155, HDL 93, triglycerides 83. CAC is zero so cardiologist says no intervention needed now and advised that diet intervention wouldn’t help me much but I do think I can cut some saturated fat in the form of dairy and red meat out and increase fiber. Family history of high cholesterol and Alzheimer’s so I’m currently doing a metabolic makeover and transitioning to 100–150g carbs a day (I have always eaten high but healthy carbs). My current goal is to lose 8lb and get my A1C down to 5 (it’s 5.5 now) I’m adding fiber with glaucomanann, psyllium, chia and flaxseeds daily. I limited fruit and whole grains (1-2 servings a day of each) and fast 16 hours a day. Legumes and nuts I eat 2-3 servings a day. Am I missing any fiber sources or supplements that are low in carbohydrates? It’s tricky to get a lot of fiber without maxing out on carbs.