Deficiencies can happen whatever it’s due to lifestyle or some other issues and as the body has evolved to function best when all the hormones are in some certain range. Too low is kinda bad as well. That’s why we have medically supervised testosterone replacement therapy.

All those supplements are completely useless, just a marketing trick and preying on insecurities.

Best non-medical boosters are balanced diet, healthy bodyweight, exercising, good sleep, minimizing stress, and getting some sun.

As the other person said, testosterone itself doesn’t cause baldness, some of it gets converted to DHT and that exasperates exacerbates any genetic predisposition to balding.
If a guys whole family line had luscious hair until old age, then it’s very unlikely to cause any balding.