@BMDoubleBlue
You may want to use Power Automate and the start and wait for an approval action block.
To execute it from Power Apps Canvas App, use the PowerApps or PowerApps (V2) trigger
(the primary difference is how you add parameters - with V2 you use the Add an Iiput at the top in the trigger block itself to add parameters - with the version 1, you have to click on Ask in PowerApps from the Dynamic Content each time). 
If you need to do advanced management of the approval where starting and waiting for approval in same action block is holding you back, then you may instead use the individual Flow blocks create an approval and wait for an approval
create an approval:
wait for an approval
PowerApps or PowerApps(V2) trigger can be added to Canvas App and you access it by NameOfFlow.Run(your arguments here matching the order and the type of the parameters declared in the Cloud Flow)
To ensure the Canvas App waits for the Run function to finish before moving to the next line in your formula in case you have another line(s) after the Run function, you must have at least one of these Respond to a PowerApp or flow blocks present in the Flow (whether you use the actual returned value or not, and whether or not all possible paths in the Flow necessarily even reach this block)
To make sure the Run function does not wait for the Run function to actually complete the Flow, then make sure to there are NO blocks of
Respond to a PowerApp or Flow
in that Flow.
The decision as to whether the Canvas App waits, or does not wait, on the Run function line of the Flow, for it to actually finish, depends on whether there is at least one Respond to a PowerApp or Flow in the Flow.
If there is at least one, the Canvas App should wait for the Flow to actually complete on the Run function call in your Canvas App before moving on to the next line(s) in your Canvas App formulas that come after the Run.
If there is no Respond to a PowerApp or Flow in the Flow, then Canvas App should not wait for the Run to finish, instead the Canvas App just fires the Flow to run, and then the Canvas App continues on to the next formula line(s) in your flow after the Run.
See if it helps @BMDoubleBlue
