Jill and I are scheduled to do the same, only from Porto to SdC. Tickets were purchased prior to the Pandemic restrictions, and they are fully changeable or refundable (my discretion), which is how I purchase all my airline tickets. . direct from the airline with flex-fares. If plans do not work out, I can cancel even if I wait until the day before departure.
In reality, because I might want to do something else if Camino de Santiagos are closed, I will probably cancel the first week of September if things are not open to tourism. The shift from using alburgues to other lodgings with private rooms and attached bathrooms for this Camino is already part of the new plan, as it is more likely that such lodging choices will be the first to re-open.
If push comes to shove, and the Caminos are open to international travelers but lodging is not (which is not a likely thing if tourism is opened), I will look at including a tent and air mattresses if I can figure out the campground or potential cold-camping situation. . . right now it seems doable at first glance. It would add an additional 2 pounds / 0.91 kg of weight to my backpack, and 12 ounces / 0.34 kg to Jill's.