That's why I want to keep it as separate tasks under a single pipeline.

Hmm Yes, if this is the case then you definitely have to have two Tasks (with execution info on each one).
So you could just create a "draft" pipeline Task and report everything to it? Does that make sense ?
(By design a pipeline is in charge of spinning the Tasks and pulling the data/metric from them if needed, in your case it sounds like you need the Tasks to push the data/metric onto the pipeline Task, this is actually doable).
So the flow can be:
Create pipeline Task (draft) Pass the pipeline Task ID to the "steps" Have the steps report to the "pipeline" TaskDoes that make sense ?