Actemra is FDA approved for GCA only.

Kevzara is FDA approved for PMR only.

Either of these biologics can be used in the United States if a patient has both PMR and GCA. Both biologics are expensive so they are not used very often unless there are "extenuating circumstances." Having a diagnosis of osteoporosis would be an extenuating circumstance.

You really shouldn't be on prednisone with known osteoporosis unless it is for the shortest amount of time as possible.
https://creakyjoints.org/living-with-arthritis/treatment-and-care/medications/guidelines-to-prevent-osteoporosis-from-steroids/
Being a relatively young male when PMR was diagnosed, my risk of osteoporosis wasn't too high. I was somewhat embarrassed whenever my rheumatologist wanted to check my bone density. However, I had other complications from long term prednisone use.

My "extenuating circumstance" was long term prednisone use and no other alternative medication worked well. After Actemra was started, I got off prednisone and several other medications which were being used to treat prednisone side effects.

These biologics don't work for everyone so that's why I usually say it depends on every person's individual circumstances. I should add that it also depends on your health care systems, insurance companies and governments.