Very good question, and great responses for many different circumstances.
For travel cancellation claims, I’ve only had one (March 2020) but can recommend RoamRight. It took 5 months, with back-and-forth documentation, but happily resulted in a full refund. For pre-travel cancellation outside of COVID circumstances, friends have endorsed Allianz and USAA.
For health scares abroad, after you’ve started travelling, if there’s one thing I would encourage, it’s to see a medical practitioner ASAP if something doesn’t feel right. For both care (you) and documentation (insurance). The worries about coverage for pre-existing conditions are unfortunately very real, but the most important thing is your health and safety
I’ve seen many threads on this forum which attest to the high quality of such visits and treatment along the
Camino de Santiago. Having been to one such clinic (which taught me to wrap a hurt ankle and dispensed a packet of anti-inflammatories – all free of charge) I am grateful to say that it is my experience as well. My situation was minor, thankfully, but everything I've heard and read leads me to trust health providers along the Camino for circumstances small and grave.
This lesson was brought home by a family member who was afraid to seek medical treatment abroad last year, despite having purchased very good travel insurance. The fear was at least twofold: 1) visiting a clinic or hospital in a foreign country (language concerns, etc, not understanding all the symptoms herself, plus general panic over where to go or what to do); and 2) worries that the visit would not be covered under insurance. Unfortunately, this month-long delay culminated in a pulmonary embolism on the flight back home, despite weeks of increasingly scary warning signs, followed by an acute emergency and weeks of hospitalization right after arrival.
Fortunately, our family member is better now and on the mend. But you can imagine how, in conversations since, we’ve urged her to utilize that overseas travel insurance next time (she is finally cleared to fly again), figuring out claims and all the rest later. It was a close call which perhaps could have been avoided. As a result, I would encourage absolutely anyone to look after their health first, letting the very understandable insurance concerns wait for later! Hopefully the companies mentioned above will be good options to set your mind at ease from the beginning. Sorry for the long answer, and above all wishing all the best! Best wishes for a very buen Camino.