There are hereditary neuropathies that really have no treatment other than symptom relief.

There are neuropathies due to some nutrient imbalance, and when that is fixed, these will improve.

There are neuropathies from trauma. These may heal but take time. Some viral infectious ones are in this category too.
Spinal pressures or nerve root compression are examples.

Neuropathy from autoimmune disease, has to be treated for the autoimmune aspect. If that is reduced, then the neuropathy can recede.

If you use a drug that is a known neuropathy causer, then continuing the drug will cause more damage. Same for toxin exposure, heavy metals, solvents, pesticides, etc.

The general postings here have been negative for sural nerve biopsy. But the sensory skin biopsies do show if nerve densities
are low or not and don't cause long term damage. All you need do is keep the skin biopsy area clean and free from infection.

The sural nerve biopsy can cause permanent damage and pain in that part of the foot. They don't always heal up well. This biopsy doesn't show much either. You already know you have problems. That is all it shows. It doesn't show WHAT is causing anything.

There are hereditary neuropathies that cause numbness and loss of muscle mass over time. Charcot Marie Tooth is the general name for them. They are diagnosed with DNA testing, but this is expensive for some people.

Lyme disease affects the nerves, and can be difficult to diagnose as well. Did you have IgG and IgM tests? Tests for antibodies? All those blood tests?