Xamarin.Forms netstandard project broken with update to VS 2017.3 - xamarin

Question

So today i made the mistake of updating my IDE to 2017.3.
I was then notified of incompatibilities such as
"NU1202: The package Xamarin.Forms 2.3.4.247 is not compatible with netstandard1.5. Package supports: list of targets such as monoandroid10, xamarinios10, etc"
After investigating the matter on google i found some information to try fix the project.
https://github.com/NancyFx/Nancy/issues/2647#issuecomment-265927440 suggests adding a frameworkmoniker to get it to build (At some point during fix attempts i had a platform warning too)
Another attempt i've made to fix the issue was recreating the project as a fresh template version of using a netstandard project (the project i've provided for repro was created during the time when project.json was still a thing)
You may ask why: While looking for the issue i read that some are false positive error messages, which can be disabled like this Package Reference Warning Ignore - However in this project type which is entirely based on .csproj again i was unable to add Xamarin.Forms 2.3.4.247.
So my question is:
Has anyone been able to get a similar project running on vs2017.3 yet?
REPRO project:
GitHub

Answer 1

After changing my project similar to a result of this:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>netstandard1.5</TargetFramework>
<PackageTargetFallback>portable-net45+win8+wpa81+wp8</PackageTargetFallback>
</PropertyGroup>
<ItemGroup>
<EmbeddedResource Include="App.xaml">
<Generator>MSBuild:UpdateDesignTimeXaml</Generator>
</EmbeddedResource>
<EmbeddedResource Include="MainPage.xaml">
<Generator>MSBuild:UpdateDesignTimeXaml</Generator>
</EmbeddedResource>
</ItemGroup>
<ItemGroup>
<PackageReference Include="Microsoft.NETCore.Portable.Compatibility" Version="1.0.1" />
<PackageReference Include="Xamarin.Forms" Version="2.3.4.247" />
</ItemGroup>
<ItemGroup>
<Compile Update="App.xaml.cs">
<DependentUpon>App.xaml</DependentUpon>
</Compile>
<Compile Update="MainPage.xaml.cs">
<DependentUpon>MainPage.xaml</DependentUpon>
</Compile>
</ItemGroup>
</Project>
the project compiled again.
<PackageTargetFallback>portable-net45+win8+wpa81+wp8</PackageTargetFallback>
fixed the issue.