Follow up on talks with Dell support:
Dell support kept pointing me to their dock (WD22TB4) as an explanation of my question:
What connections and resolutions does the Precision 7770 with NVidia RTX A1000 support via the Thunderbolt 4 connector?
Based on the responses I received and my own testing, the laptop is limited to a single HDMI output at full bandwidth or multiple DisplayPort outputs at full bandwidth using the NVidia graphics system. When using the Intel graphics system, the displays ran fine (4K@60Hz) in all cases.
The solution I landed on was to purchase two Plugable DisplayPort to HDMI 2.0 Active Adapters (Model DP-HDMI) in order to allow the laptop to utilize the DisplayPort connections of the dock and thereby run my external monitors on the A1000 graphics card at full 4K@60Hz resolution.
Leaving this here in case other Dell users run into the same issue(s) I have, but want to use this really nice dock.
Thanks for the look at the diagnostics Joshua, but I think this isn’t a Plugable issue.