Regarding the whole age thing, I wouldn't say it's ageist to not be into a movie where an 80+ year old is being presented as an action hero.
It doesn't matter to me too much. With few exceptions all action heroes are being portrayed via a combination of an actor, stunt performers, and special effects. None of this is real so having Harrison play the role now is not overly egregious to me.
Keanu Reeves is almost 60 yet we see John Wick fall several stories, bounce off a metal beam, and walks away with a slight limp as he barely slows down. As opposed to real life where he'd be en route to a hospital or the morgue. Is it different when the actor is 80? Sure, but both cases require suspension of disbelief.
I do think they could have put him in situations that were more believable. He was still effective as Han Solo because he's mostly flying a ship and firing a blaster. Indy has him jumping from moving vehicles, playing chicken with a subway car on horseback, amongst other stuff.
It's a weird dichotomy in this movie because they do lean into the story of a man who is not the action hero he once was, and has to find himself again, but then impose no limits on what he can do. Maybe there could have been a happy medium.