Import local users to active directory?

[denethor]

We started with QNAP years ago as small shop with just a handful of users and one NAS with all Mac users so there was no need for a directory at the time.
This has grown to 3 departmental NAS boxes and a hundred or so user accounts that are all just local users on the QNAP.
We have since moved on to hosted Office 365 (which has its own hosted Azure AD, kind of limited though) and I just installed a new Windows Server with AD to sync up with the Office365 directory (which doesn't work for what I wanted but thats another story, it only syncs local AD TO 365, I can't pull all my existing 365 users to the AD).
My question is, and sorry if this has been answered previously but I searched and didn't find it (other than basically this same post I made 2yrs ago).
Is there away for me to import all of my QNAP user accounts and passwords to the new AD server?
I don't want to hand create 100s of users and even worse, if I did that everyone would have to give me their pw or I'd have to set some temp password and force them to change it on next login which they could then set it back to their old PW.
The new AD server is mostly for our new VPN so people can work from home or on the road securely and the VPN uses AD to authenticate the user.
I figure if I now have to maintain an AD server, everything might as well sync to it.
It's been 15yrs since I had to admin a Windows server, so please be as specific as possible when giving advice. I am very technical minded though and have worked in IT for over 30 years.

Thank you in advance for any help.

[storageman]

What is wrong with AD Integration?