Stem cell therapies for hip osteoarthritis are relatively new, have not been subjected to rigorous scientific study, and hence are not generally covered by insurance. There is also no knowledge of long-term effectiveness because the treatment is so new. If your intent is to postpone hip replacement surgery, and you can afford the treatment, it might be worth a try, especially if you are relatively young. Perhaps you can research local clinical studies of the treatment in your area and find one that will accept you.
Here is a very recent article discussing the matter: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8832617/

With other conservative methods like hyaluronic acid (HA) effects seem to fade after 6 months to one year, and as with other non-surgical interventions, there are limits to who they can be expected to help. For example, when my hips needed replacement over 15 years ago, they were already severely eroded by arthritis - both cartilage and bone surface had significant damage. So even though I was only in my 50's, conservative treatment, including steroid injections & therapy, were completely ineffective.

Are you interested in trying to find a clinical trial?
Sue