What should I do, if anything, about these branches that were gnawed on by a squirrel. One doesn't look that bad, but one looks pretty chewed through. The leaves on that branch look fine though.

It looks like their heeling nicely. I might just leave them alone. Get rid of the squirrels tho.😎

Maybe you could trap and release them far away? I've had to do that a number of times to save my plants. Today I noticed that all of my potatoes had their leaves stripped off.