Create hierarchical dropdowns in PowerApps based on two different SharePoint lists

I have created a time tracker app for back-office tasks that track multiple projects like answering correspondence or updating a members account. Per the requirements there are 4 dropdowns Project, Actions, CPC sub-Action (a dropdown that only displays if project value starts with CPC), and Outcome. The value of each dropdown should be dependent on the value selected on the previous dropdown and the values for the dropdowns is pulled from different SharePoint lists. I pull values from a SharePoint list as these will change from time to time. All the results are then written to another SharePoint list as text.

I have no issues with CPC sub-Action as I use a condition on DisplyMode property for that dropdown because this field is only applicable for only one type of Project value.

If(
    Or(IsBlank(DpdAction.SelectedText), Not(StartsWith(DpdProcess.Selected.Value,"CPC"))),
    DisplayMode.Disabled,
    DisplayMode.Edit
)

It is also easy to set up a relationship between the Project and Action dropdown because they use the same SharePoint list. I could extend that relationship to Outcomes by adding another column but since I have to account for every combination of Project/Action/Outcome this would become cumbersome as there are like 5-10 different outcomes and they are sometimes unique by Project.

Code used in Item property to limit Action dropdown values:

Sort(Distinct(Filter('Cascading List', Title = DpdProcess.Selected.Value),Action),Value)

Example of Cascading List SharePoint list:

This Cascading List SharePoint list is rather contained and only has 129 rows but this could explode to over a thousand rows if I added outcomes. Thus I thought it would be easier to create a separate Outcomes SharePoint list that only has about 20 rows and create some sort of relationship in the Items property for the Outcome dropdown by matching common values like project name between the Cascading List SharePoint list and Outcomes.

Example of Outcomes SharePoint list:

Is this possible using filter and referencing two SharePoint list? I did look at some of the recommended questions that have been answered but since I learned PowerApps base one youtube video I think I am still too dumb to understand, reinterpret and apply the solutions provided.