I'm building an app that is connected to a SharePoint list. In this list there is a place to take notes. I've turned on versioning so that

Viewing the Versioning from the SharePoint List in the PowerApp

Could you please share a bit more about your scenario? Do you turn on the "Item Version History" option within "Versioning Settings" of your List Settings?

Do you want to view all version of Notes from a SP List within your app?

If you want to view all version of Notes from a SP List within your app, I afraid that there is no way to achieve your needs in PowerApps currently.

There is no function/way supported within PowerApps to retrieve all versions of Record history within a canvas app. As an alternative solution, I think the MS Flow (Power Automate) could achieve your needs. Please check and see if the following blog would help in your scenario:

https://johnliu.net/blog/2018/5/microsoft-flow-sharepoint-trigger-on-specific-fields-changed-via-sp-http-request?rq=version

On your side, you could consider set up a flow, add "PowerApps" button as the trigger of hte flow, specified the List Item ID parameter (which needs to be passed from a canvas app) using "Ask in PowerApps" dynamic content within the "Send an HTTP request to SharePoint" action. Then add a "Response" action within your flow to return the retrieved table value back to your app.

More details about returning a Table value back to a canvas app, please check the following blog:

https://powerapps.microsoft.com/en-us/blog/return-an-array-from-flow-to-powerapps-response-method/

Then you could create a canvas app, add your SP List as data source in it. Add a Gallery (Gallery1) within your app, connect it to your SP List, configure the OnSelect property of Gallery to connect to above flow, in other words, set the OnSelect property of the Gallery to following:

ClearCollect(NotesCollection, 'FlowName'.Run(ThisItem.ID))

Add another Gallery (Gallery2) in your app, set the Items property to following:

NotesCollection

When you click specific item in your Gallery, it would fire the flow to retrieve the related versions of notes, and return back to your app, then it could be displayed within the Gallery2.

More details about firing a flow from an app, please check the following article or video:

https://docs.microsoft.com/en-us/powerapps/maker/canvas-apps/using-logic-flows

https://www.youtube.com/watch?v=1wl9AtxWdkg

Best regards,