The latest agent versions are compatible with 13.4. I don't think the Android OEM Specific agent will be compatible with an Android 9 device however, and if they are they won't be for long. You should consider deploying with the generic Android Enterprise agent instead. 

Thanks for that.  We have not rolled out our plan for Android Enterprise at the moment but agree we need to do that soon.  We are a little unique where we are providing the devices with our software and the MDM software to our customers so I'm not sure the best way to manage that.

Since the latest is compatible and to keep from having to manage multiple APKs per Android OS, how can I change our add devices rule to use a specific APK?  Right now, I can only select the manufacturer but I can't seem to be able to select a specific agent.

From the release notes it looks like Android 9.0 support was started in OEM specific agent version 13.7.0.

The OEM specific agent relies on Device Administrator API based management which is deprecated in Android Q. If those devices out in the field ever get an OTA upgrade to Q from Samsung they would end up completely orphaned. Then, to re-enroll as Android Enterprise you'd actually have to Factory Reset them first as AEDO enrollment requires that you start from a factory default state. SOTI is working with Zebra, and possibly Samsung on a path for DA->DO migration without a Factory Reset but I wouldn't count on that option, especially since it will also very likely require a MobiControl upgrade to 15+.

Under Android Enterprise you do not manage a specific agent per device because every device gets the same agent, the concept of an OEM specific agent goes away. There are supplemental OEM specific plugins that you can install to add extra value adds, but SOTI actually bakes in a lot of the value adds for Samsung management directly into their AE agent.

Good info, sounds like we will be forced into that pretty soon as our new devices start rolling out with 10.  For the ones in the field we have the block OS upgrade setting pushed out through Mobi on all of them so hopefully that will help prevent at least those to get upgrade OTA.

We stayed away from AE originally as in theory these are not our devices (we are selling with our software and providing the MDM).  We are obviously going to have to change that mindset and if the client ever wanted to use the tablet away from our custom software & MDM they would need to un-enroll and factory reset, I would assume.

It depends on how you set it up. With Android Enterprise you have multiple management modes. If the end customer owns the device then maybe you should leverage a BYOD scenario where you are the Profile Owner, administering just the contents of that partition. If you are the Device Owner and want to comprehensively manage the device as a Work Managed device then you would enroll under AEDO. If you enroll as AEDO then you can't unenroll and factory reset from the device level as it would just re-enroll into the EMM that it is bound to. 

We are kind of in the middle ground here where we sell the the device but we control all aspects of it.  This is in the transportation industry so the devices stays in a vehicle and are 100% only used for our software.  So technically we do not own the hardware, but we manage it like we do with the kiosk, etc... and we also own the data plan with the device.  All of our customers' MDM controlled through our dedicated deployment server that we host and we have the customer devices and permissions separated out by groups.  I need to do some more reading around AE so I can come up with the best plan moving forward.