@babs10 Here are some ideas about the cost of drugs, and insurance coverage:
Have you tried various kinds of appeals to your insurance company? Your doctor can fill out some special forms that say you're at high risk of fracture. In that case, many insurance companies will cover other, more expensive drugs that are not on their usual formulary. You can ask if your insurance company has a Case Manager you can speak to. And, you can possibly switch to a better drug plan for next year. (The Medicare website lets you test out what different companies will pay for specific drugs.)

Many drug manufacturers (like Radius Health for Tymlos, who promises to respond quickly) offer financial assistance if your income is below a certain level. Also, there are non-profit foundations like "The Assistance Fund" that might possibly help (though it may take several months to get on board with them.) Some (public?) hospitals (through their outpatient specialty pharmacy) have special reduced rates for certain expensive drugs. Even big chain pharmacies like CVS may offer financial assistance.

Another trick is that your doctor could possibly write it up in a way so that your Part B will cover it, instead of Part D. What's good about that is that your copays would count toward your annual out-of-pocket maximum, which could add up fast, in a few months, and then you'd pay nothing for the rest of the year. (They might not allow it, though. I'm not sure.)

How terrific that you hiked the Camino de Santiago! And a Europe bike trip, too. Good for you! They say that having strong muscles is great for protecting our bones.

I was like you, wanted to avoid medications and possible side effects, and I ended up with 2 vertebral compression fractures at age 71. My endocrinologist told me that after a certain point, nutrition and exercise alone are not helpful enough. The fracture experiences were hell, extremely painful and debilitating A year and a half later, the fracture experience still adversely affects my health and quality of life. I'd advise you to avoid that at all costs. So please do your research, leaving no stone unturned, and then make a decision. Good luck!