The easy thing:
I've noticed that when we call the help (F1) on any Affinity Application it shows a simple HTML browser window that is probably using Internet Explorer API without toolbars/menus...
But when I get the HTML file path URL and drop it on Microsoft Edge (chrome based) I can use the built in Text to Speech feature (Ctrl + Shift + U) to read the help for me so I don't need to stop what I'm doing to read... I can listen to it while I'm still using the App 🙂
I'm not saying to change the engine completely, cos some PCs don't have the new MS Edge installed, but it could be a feature on settings for users to decide what browser engine they like more.
The hard thing:
Another advanced approach would be using Cortana API to search inside the affinity app help using Windows voice or text search 🙂