Juan: if you have Project for the web or Planner premium running in a 'named' environment (or even Default), keep in mind the Planner Power app is running behind the scenes when you setup that environment. If you go into 'Power Apps' in your O365 'waffle', in the upper right you'll see 'Environment' and then a name. This will drop down and allow you to select the specific technical environment you want to access the Planner Power App within (you can have multiple ones, for different groups like IT, finance, etc., or Prod + Dev). Select the name of the environment (Default for the core out of the box one everyone has access to by default). then scroll down. It will show 'Your apps' for that environment. You'll see a 'Project' app, hover over the three vertical dots, and you'll see a 'Play' button. Hit that, and it'll launch into the Planner Power App. The out of the box one has a very limited set of views and fields, and no reports displayed, but you'll see a list of all the projects you are managing in Planner premium or Project for the web today. This is where a 'solution' can be built or deployed.
All of your modifications to the Power App (adding fields, adjusting views, adding security, etc.) happy within the Power apps portal make.powerapps.com back end which you will now be in.
If you'd like to see an example of a solution up and running, here's a link to a video of one we developed, aligned with how PMOs typically function. Hope this helps.
https://youtu.be/h0nEIcAQqYU?si=mRWAignmM-24yg88