I too have used pump DEF with no problems.
From what little I know about it, there is an ISO std 22241 for DEF that specs the purity of the urea, % urea, deionized water, and level of contaminates. If it’s API certified, it means it’s tested regularly. I suppose a mfr could use agricultural Urea and lower quality water if they don’t claim meeting ISO and/or skip the API cert.
Some pumps or the company’s website will list what their DEF meets. For example (see the droplet bubbles for ISO.):
https://pilotflyingj.com/media/36698/pilot-def.pdf
The boxed stuff from Peak Blue DEF and Bluesky DEF label theirs as ISO and API.
Re the Dodge dealer comment, maybe it’s like my Ford dealer always wanting me to use their oil, filters, fuel additive, service dept, etc.