Wallpaper Lock

No.

I try to give end users as much freedom as possible.

Nope

No we do not. And when we did we gave end-users the option to use their own. 

We used to but experienced bad user feedback. Now we deploy a default wallpaper and allow users to change it if they want.

25 years of Mac admin, 15 years of Casper/Jamf, not once at any of those organizations - typically set loginwindow background (RIP) and user background, but not lock.

Both yes and no. We actually us it to inform our user when their iPads are out of date. When a new update comes we let the users know and if they don't update their iPads the devices background goes all red. Ounce they update it can be set to whatever the user wants it to be. 

No.  We'll set it to our corp. defaults, but not lock it.

no, we don't. But while the initiating rollout / enrollment, we serve a company wallpaper to the client and set it as default. The user can change the wallpaper, if wanted. The same procedure we do with the Dock. The users dock is configurated, but the user can change the dock items if he want.

I like this idea. Can you elaborate more on how to do this? 

Here are some details that will hopefully help you out. 

First you need to be able to identify which version of iOS each device is on. To do this we created three 'Smart Device Groups':

1. A few iOS versions back (iOS < 16.7.1 for example).
2. The iOS version you would like them to be on (iOS 17 for example)
3. And finally iOS version ahead of where they should be at (iOS 17.2)

Just follow the sections when creating a new 'Smart Device Group'

1. Mobile Device Group, just name it
2. Criteria, I'm sure there are a few ways, but we used the logic of, if the device is supervised and has iOS version <,> or = to versions in question. 
3. Automated Management, we used the function 'Set Wallpaper' 

Few things to note about this, is that you'll have to go and update these 'Smart Device Groups' every time you want to implement an iOS change. Also it takes 24 hours for the change to take affect, so even after the update the wallpaper will stay the same until it checks in again.