best practice: Upgrade Android 7 -> 8
Hard to say which way is really best practice.
When i remember correct (it's long time ago we tested that) the Update from 7 to 8 resets all data (without enterprise partition). It could be not happen but needed to reset all becauseo of DO or DA mode etc.. I really not sure but i think we had many problems on TC51 without reset it completely.
Even you are "only" talking about 80 devices, which shouldn't be that hard to update.
We have decided to swap those devices 1:1. So: Install a new device with android 8, enrolled it 1:1 as the old one from the users is configured and swap them directly. Then getting the old one with android 7 back and upgrade them centrally via SD-card including complete factory reset to be sure all is clean for a reinstallation.
So the user don't have to do many actions, just use the new device (maybe some user specific settings to be made and not centrally configurable settings to be made). But no Barcode scanning, waiting, downloading etc. with risk of false handling, creating support cases, problems and a long time no useable device for the user.
I think the idea with the swap is not bad.
However, this would only be feasible for us if the devices were all close by.
Unfortunately, these 80 devices are distributed from Chile, Brazil, America to France and elsewhere. Therefore, this option is probably out.
I had hoped that it might have worked easier with the "Migrate to Android Enterprise Button" + a Syncrule + Script.
If you had enrolled the Android 7 devices under Android Enterprise instead of Device Administrator then you could have upgraded cleanly from 7 to 8 and the devices would have continued to stay enrolled. The issue you face is that you're now having to convert from DA to DO based management which typically would require a full factory reset and re-enrollment of the devices in order to convert them over. This is due to a fundamental principal of Android Enterprise that dictates that the Device Owner level privilege can only be applied on devices in a factory default state in order to protect end user consumers who previously were inadvertently granting random applications from the Play Store full Device Administrator privileges without realizing the power that they were giving over to a potentially malicious app.
Zebra and a few EMM providers however, including SOTI, have teamed up to provide a non-standard mechanism for migrating from DA to DO with their devices. This method is still by no means that clean and is subject to failure, but it is potentially better than have to retrieve and factory reset and re-enroll all of the existing estate of devices, especially if they're distributed out across multiple environments, which is often the case with WAN devices.
Given that you only have 80 devices and they're WiFi only and therefore likely to be in a limited number of physical locations my recommendation would be to pursue the manual factory reset and re-enroll. It is relatively simple to provide instructions/documentation on how to access StageNow, scan a factory reset barcode, and then another series of barcodes to re-enroll under AEDO.
Note regardless of what method you chose to convert the devices from DA to DO you will also have to reconstruct all Profiles under Android Enterprise as the Android Classic (DA) Profiles will not apply.
Utilizing and SDCard with all firmware files and an .xml and .upl file makes the upgrade MUCH easier than going through and installing zip files one by one.
Rather than using stageNow to create the files, I just made the xml and upl files myself and have been very successful. https://www.zebra.com/us/en/support-downloads/knowledge-articles/evm/OS-Update-multiple-packages-using-SOTI-MobiControl-Mxconfig-Script.html
You will also need to use the FactoryReset zip and the Enterprise Reset zip after the upgrade to ensure all old Soti cache is removed.
that sounds really good! Thanks for this approach, we will definitely take a closer look.
Have a nice day