The best news is that you are 84 and feel good. Congratulations!
That being said, apologies if I've misinterpreted any of your posts so far...
It sounds like you have signed up for lab tests with AHNP to start exploring possible areas needing improvement to reduce risk of cognitive decline. Stratgene will provide you with interpretation of your 23&Me genetic information. The Stratgene website has a short video to help people decide if their service will be of benefit; you may want to watch this. Some of our members embrace the additional information at the beginning of their journey, while others are already overwhelmed with data and suggestions, and decide to wait until they feel more confident of their ability to process the information. And some of us have not done any indepth genetic testing or interpretation.
What role are you expecting the health coach to fill for you, and how did you find the one whose credentials you liked? The health coaches I am familiar with do not interpret test results, but perhaps this person does. Some health coaches give a short session for free to help determine if the relationship will be a good match. You may want to look into this.
In my experience, Medicare won't reimburse for the labs or health coaching. Medicare insurance is the most restrictive on covering lab work, and require appropriate diagnoses for each lab test to determine coverage. I don't think any diagnoses are used to order labs through AHNP. Most Medicares do not cover health coaches, but your specific insurance may differ. It doesn't hurt to call and find out.
Hope this helps. Taking small steps in the right direction are still very helpful to reach your goals. Take on what you can financially, add on as necessary. Focusing on nutrition, exercise, sleep, and stress management are good places to start.