There are many things to ask to my manager (non-meeting days, remove non mandatory people from invites, open team discussion on the topic). I guess this is more of a culture thing at work where everyone is "expected" to show up. I see my boss' situation as even worst (although one might argue that that is his job, I see this as quite unhealthy no matter the role)

First off, I would set the strict max 30 minutes time limit for each and every meeting. If it’s not enough to solve something: do a follow up next day but ask everyone to prepare properly. Or just move the discussion to emails.

2nd: be an ass as a moderator. Cut all the small talk, chit chat, warm ups, derailing, or ad hoc brainstorming (usually performed by two people while the rest of the attendees are slowly dying inside).

I wouldn't ask them the question you just asked them.