munki VS autopkgr

In the non-MDM tool space, look into Munki https://www.munki.org/munki/

this experience is an indication that the opco didn't hire the right expertise. If the numbers you quoted ie 30k desktops, 50k total were not macs, it's clear that the org didn't have the kind of mac experience needed to manage a a new org with all macs.

It's entirely possible for administration of macs.

Start networking/asking around with places like Disney or Pixar, etc which have a large amount of graphic artists using macs. For example, from Disney https://github.com/munki/munki gets you to a certain point.

Other tools like Kandji (lightweight) and the 900 lb gorilla in the industry Jamf gets you the other management / administration bits needed

If this opco that you referred to never got a Jamf rep to work with them and to try out their (yes, very expensive) products, then this is mostly inexperience with the mac ecosystem.

There's a decent open source option: https://github.com/munki/munki

I got to use it at work at Meta (as end user), and it seemed to work quite well. They delivered Android SDKs/IDEs and a bunch of other things that I'd personally install through Brew with Munki.

Munki is not an MDM and I recently learned there's this project called Installomator that might help.

Or Munki

This is a feature of munki called default manifest resolution. Though I prefer to avoid this and explicitly set the client identifier for all devices.

another option is munki https://github.com/munki/munki, for the software update part,

Would it be Autopkg https://github.com/autopkg/autopkg or autopkgr https://github.com/lindegroup/autopkgr by any chance?

Definitely AutoPkgr. Keep in mind, learning to work in the “command line” is the single best & most thing you can do to advance as an (aspiring) IT admin.

AutoPkgr (GUI for AutoPkg) https://github.com/lindegroup/autopkgr

AutoPkgr makes it simple to install and configure AutoPkg quickly and reliably in the Mac OS. It's the easy way to take advantage of automated macOS software packaging and distribution without the need for command-line methods. gabhain explains, "For Mac downloads AutoPkgr is a god send, and you can make some interesting workflows and automations.”

if you are using autopkgr, you may be running into this bug: https://github.com/lindegroup/autopkgr/issues/657. like the other guy said if you make changes to your munki repo, make catalogs will need to be run at the end.