Android 8 on Zebra devices will force you to be under Android Enterprise management and I presume you'll want to use Fully Managed/ DO . If the devices are currently enrolled in SOTI under Android Plus (Device Administrator) then you will need to get them managed under DO first before upgrading them to Android 8, otherwise you will lose connection to them and they will end up in an unmanaged state requiring manual intervention. Typically I would historically have recommended a factory reset of the devices and a re-enrollment under AEDO. However, Zebra & SOTI have worked together and they do offer a path for DA->DO migration while keeping the devices enrolled. I have never undertaken this procedure before as I personally don't trust it (DO is supposed to happen from a Factory Default state by design), but it could potentially work in your situation. 

• Recreate all your Profiles and Configurations as Work Managed so they can apply to the AEDO managed devices after they are converted from Android+ (DA)
• Use the DA->DO Migration Process to convert your devices to AEDO. 
• Use a File Sync Rule to deliver the update zip, and a post sync install_system_update script to execute the .zip in order to get the devices upgraded to A8. 

https://www.soti.net/mc/help/v15.2/en/console/devices/managing/enrollment/androidplus/enterprise/migrate_zebra_ae.html?hl=migrate

Dear Matt Dermody!

Thank you your help and infos.