How can I verify the security of my MacBook after an Apple tech remained remotely logged in?

Concerned...Yesterday a Mac tech (Matthew) from Apple spent over an hour on the phone assisting me with my MacBook. He had access to the system settings, helped reset my Apple Id Password, I logged in and out of iCloud (which only asks for my MacBook login password, not Apple Id's) and more with his guidance. Seemed super nice, and wasn't in a hurry or concerned about time spent. We eventually ended convo, and I proceeded to work on security issues (changing logins, passwords, moving docs, etc.) only to realize two hours later that Matthew was still remotely logged into my laptop. I immediately ended that, but am now bothered and paranoid. If he was a true Apple tech (which I did hear other agents in the background, but I suppose that could be recorded chatter?) why wouldn't he disconnect remote access when he ended the call or at the very least be disconnected when starting another support call?

The whole point for the call was with security issues and now I am unsettled and not sure if I compromised my security further. Is there any way to know for sure? Where could I look to see if his specific access during those two hours did or changed anything? Are there any specific ways or guidance suggestions for this?

[Re-Titled by Moderator]

Original Title: Apple agent did not end remote access after call had ended...what steps to do now, trying to know more about it if possible?