Sideloaded UWP Javascript Hosted Web App doesn't display PDFs - pdf

Question

I have a UWP Hosted Web App (Blank Javascript) I am using to wrap a locally hosted website that has embedded PDFs. PDFs are displayed in a single-page application powered by Vue.js.
The intent is to create a locked-down kiosk on a machine running Windows 10 Pro.
I have verified the URL is locally accessible on the target machine from an Edge browser, and that each PDF is visible, but the PDFs do not display from within the UWP application.
To test further, I found a site with sample PDFs embedded four ways: https://pdfobject.com/static.html. All four PDFs load fine in MS Edge but do not load at all in my app.
A sample package.appxmanifest using that test url:
<?xml version="1.0" encoding="utf-8"?>
<Package xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10" xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest" xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10" xmlns:uap3="http://schemas.microsoft.com/appx/manifest/uap/windows10/3" xmlns:uap4="http://schemas.microsoft.com/appx/manifest/uap/windows10/4" IgnorableNamespaces="uap mp uap3 uap4">
<Identity Name="SampleFoodsKiosk" Version="1.0.19.0" Publisher="CN=self" />
<mp:PhoneIdentity PhoneProductId="2b72d1a3-29c9-4694-8514-09e553e6377a" PhonePublisherId="00000000-0000-0000-0000-000000000000" />
<Properties>
<DisplayName>Sample Foodservice Kiosk</DisplayName>
<PublisherDisplayName>Self</PublisherDisplayName>
<Logo>images\storelogo.png</Logo>
</Properties>
<Dependencies>
<TargetDeviceFamily Name="Windows.Universal" MinVersion="10.0.0.0" MaxVersionTested="10.0.0.0" />
</Dependencies>
<Resources>
<Resource Language="x-generate" />
</Resources>
<Applications>
<Application Id="App" StartPage="https://pdfobject.com/static.html">
<uap:ApplicationContentUriRules>
<uap:Rule Match="http://www.Samplekiosk.com" Type="include" WindowsRuntimeAccess="all" />
<uap:Rule Match="http://Samplefoods" Type="include" WindowsRuntimeAccess="all" />
<uap:Rule Match="https://pdfobject.com/static.html" Type="include" WindowsRuntimeAccess="all" />
</uap:ApplicationContentUriRules>
<uap:VisualElements DisplayName="Sample Foods" Description="Sample Foodservice Kiosk" BackgroundColor="transparent" Square150x150Logo="images\Square150x150Logo.png" Square44x44Logo="images\Square44x44Logo.png">
<uap:DefaultTile Wide310x150Logo="images\Wide310x150Logo.png" Square310x310Logo="images\LargeTile.png" Square71x71Logo="images\SmallTile.png"></uap:DefaultTile>
<uap:SplashScreen Image="images\splashscreen.png" />
</uap:VisualElements>
<Extensions>
<uap:Extension Category="windows.lockScreenCall" />
<uap:Extension Category="windows.aboveLockScreen" />
</Extensions>
</Application>
</Applications>
<Capabilities>
<Capability Name="internetClient" />
</Capabilities>
</Package>
Are hosted web apps incapable of displaying embedded PDFs at all? If so, what other method can I use for displaying inline PDFs?
Other posts on getting PDFs to display in UWP appear to be focused on reading the stream and displaying it as an image, but I'm not sure how that would work with a hosted app (even if it IS local).
Other things I've tried:
Chrome Kiosk by replacing the shell (doesn't work in Win10 Pro)
Adding every available UWP Capability