I'll first state that we try to use Jamf as our main inventory system for Macs + iOS devices and keep as much data in there as possible. The fields we need are there and it usually makes sense to have the least amount of tools doing the same/similar jobs.
We enroll all devices in DEP. Our PreStage Enrollment settings for "User and Location" and "PO Date" are essentially all blank as we use a single DEP Enrollment for all devices (we buy sporadically in varying numbers). When a device is going through DEP after it has been with another user, this DEP process is essentially blanking out the PO Date and User fields and clearing out any data we placed in there. We can prep for this if IT is doing this imaging process as we just jot down PO/Building/etc and place it back in after the device is all set up. This is very problematic for company-owned iOS devices as users are a lot more familiar with wiping those than Macs and do it more often (though Macs can sometimes still happen).
So my main question is.. With DEP, has Jamf become less usable as a source of truth for the majority of our IT Asset tracking needs? I believe years ago the blank fields wouldn't override existing text, it popped up in maybe 2018 or 2019. Do most of you use another tool for tracking assets? Or do you have different DEP Enrollments for each batch of purchases?
I like Jamf too because it contains all the fields you need etc. We use another database to keep track of our PC's and well, adding iPad in there sees redundant, but hey, I am not the boss. The prestage enrolments is where you put that data, and if you could have one prestage enrolment per device ( I have 400 devices, so easy to do), you would never have to worry about losing the data when reimaging an iPad. But apparently that is not a good idea to have one prestage per device, which is REALLY too bad! I suppose if you manage 20,000 iPads, this would not work..too tedious...maybe..
Check what your flushing for re-enrollement in Jamf Pro:
Settings - Global Management - Re-enrollement
I would of thought fields like PO Data are just treated the same as normal extension attribute fields, so it you have the box checked to flush these on re-enrollement then that info will be lost each time they get re-enrolled with DEP
However saying that, Jamf Pro is not a CMDB in any shape or form to record this type of information
(If your using a ITSM tool to cap outer support tickets then many have or have an option of using CMDB).
It would be wise to invest in a dedicated tool like ServiceNOW which has native integration into Jamf to keep track of IT assets and purchase information alike.