Here are a few exercises you can try for uour foot. You may not be able to do them all but just do what you can.
Exercises to counter foot pronation focus on strengthening intrinsic foot muscles, the calf, and hip/gluteal muscles, and include towel scrunches, big toe pushes, heel raises, tip-toe walking, and glute-strengthening exercises like the glute bridge. These movements help to support the arch, improve balance, and correct the inward rolling motion characteristic of pronated feet.
Foot and Ankle Strengthening Exercises
Towel Scrunches: Sit with your feet flat on the floor and a towel in front of you. Use your toes to scrunch the towel towards you, building strength in the intrinsic muscles of your feet.
Big Toe Push: While standing, lift your arches by rolling your weight to the outer edges of your feet and gently pressing your big toes into the floor.
Heel Raises: Stand on a step or the floor and slowly rise up onto your toes, strengthening the calf muscles and ankle joint.
Toe Tapping: Sit with your feet flat and repeatedly tap your toes on the floor, which helps strengthen the muscles that support the shin and ankle.
Tip-Toe Walking: Walk on your tiptoes to strengthen your foot, ankle, and leg muscles and improve balance.
Arch Lifts: Lie with your feet flat and lift your arches by squeezing your heel, big toe, and pinky toe towards the center of the foot.
Those along with using your splint should all help.
Yes, you sent me a pic of your quad stick.